Massive Stones Keep Coming: Botswana's Prolific Karowe Mine Yields 472-Carat Diamond

Lucara Diamond Corp. is continuing to recover massive diamonds at its Karowe Mine in Botswana. The latest find is a 472-carat "top light brown" gem that rates as the third-largest ever discovered at the prolific mine.

Karowe has assembled an impressive track record for producing the world’s largest fine diamonds. The 1,109-carat Lesedi La Rona and the 813-carat Constellation were both mined there in November 2015. Four diamonds greater that 100 carats already have been recovered during the first quarter of 2018, according to the Vancouver-headquartered mining company.

The recent proliferation of massive stones at Karowe can be attributed to Lucara's investment in X-ray transmission (XRT) imaging technology. The new machines are calibrated to extract 100-carat-plus diamonds by monitoring X-ray luminescence, atomic density and transparency. Previously, large diamonds might have been mistaken as worthless rocks and pulverized by a crushing device.

“The early sampling work [at] Karowe was done with equipment that really was not optimal and they ended up breaking a lot of diamonds,” Chief Executive Officer Eira Thomas told Bloomberg.com. “When we went into commercial production we expected to do better, but we had no idea that the diamonds that were being broken were so much larger. ”

Interestingly, the largest diamond ever found at Karowe — the 1,109-carat Lesedi La Rona — was actually a chunk of a broken diamond. The other part weighed 373 carats.

The unnamed 472-carat rough diamond is expected to be sold alongside Lucara's other top finds of 2018 at the company's first Exceptional Stone Tender later this year.

Lucara's roster of extremely large stones have generated seven-figure paydays for the company. Lesedi La Rona was sold for $53 million; Constellation earned $63 million; and the chunk that broke off Lesedi La Rona delivered $17.5 million.

While brown-tinted diamonds tend to yield lower prices than colorless or fancy-colored diamonds, Thomas — also known as Canada's Queen of Diamonds — believes the extraordinary size of Lucara's newest find may alter the standard valuation process. She told Bloomberg.com that some manufacturers may actually choose to accentuate the color through polishing.

“They tend to command a lot of interest because there are a variety of views on what can be done with stones of that color,” said Thomas.

The 472-carat diamond currently occupies the 31st position on the Wikipedia list of the largest rough diamonds of all time. Lesedi La Rona rates #2 and the Constellation is #7.

Credit: Image courtesy of Lucara Diamond Corp.

N.H. Granny Gives Up Her Own Engagement Ring So Young Waiter Can Propose to His Girlfriend

A New Hampshire granny has earned internet stardom after generously gifting her own diamond engagement ring to a young waiter so he could propose to his girlfriend.

"It was just the right thing to do," Concord native Sharon Heinemann told local TV station WMUR. "I just did it, you know. He loved her, and he didn’t have a ring."

Last week, Heinemann and her two sisters ventured to Boston to see rock star Pink in concert. Before the show, they stopped in at Legal Sea Foods and struck up a conversation with their waiter, Mattheus Gomes.

Sister Ginny Krowe explained: "Mattheus, a very handsome gentleman, waited on us and served us, and I got to chatting with him and asked him if he had a girlfriend."

Gomes told the ladies that he was deeply in love with his girlfriend, Maria, who also worked at the restaurant.

He also revealed that he was planning a proposal, but he couldn't afford a ring.

Without hesitation Heinemann plucked the engagement ring from her finger and handed it to Gomes.

The waiter called for his girlfriend and got down on one knee.

Krowe recounted the proposal: “He says, ‘Maria, I love you. Will you marry me?' She was crying. She says, ‘Yes, yes, Mattheus.'”

Later on, Maria got to meet the woman who helped make her dreams come true. The two ladies posed with their rings — Maria proudly wearing her new diamond engagement ring and Sharon wearing her diamond wedding band.

Mattheus and Maria have already invited the three New Hampshire sisters to their wedding. When a reporter for WMUR asked who will be attending, all three enthusiastically raised their hands.

Legal Sea Foods made the day even more special by picking up the lunch tab for the sisters.

When asked how she felt about giving up her engagement ring to help the young couple, Heinemann said she felt "immensely happy. It made me feel good."

Heinemann and her sisters are now internet stars, as their story has been picked up by top news outlets, such as Yahoo!, The Sun, The Daily Mail and ABC.

Credits: Screen captures via YouTube.com/WMUR-TV.

Yale's Peabody Museum Showcases Stunning, Rarely Seen Formations of California Gold

One of the world's finest collections of California gold made its debut Saturday at the Yale Peabody Museum of Natural History in New Haven, Conn. The exhibition features 23 natural formations of gold, some of which resemble leaves, coral and skeletons.

“The Mockingbird” measures 2.5 x 2.0 x 1.0 inches and features skeletal octahedral gold crystals stacked on minor quartz crystals. It was discovered at the Mockingbird Mine, Mariposa County, California.

Most were collected over the past 25 years, although two specimens of crystallized gold were mined in the 1850s during the California Gold Rush.

“The Eagle,” which measures 2.5 x 2.5 x 2.0 inches, was mined in the 1850s in Placer County, Calif. It features clusters of octahedral hopper gold crystals.

“This collection is incredible,” said Richard Kissel, the Peabody’s director of exhibitions and public programs. “The gold specimens on view are of superior quality — impressive physically and stunning aesthetically. The exhibit highlights the specimens’ beauty while offering insight into the history and science of gold mining.”

“Colorado Quartz 2” measures 2.37 x 1.6 x 1.0 inches. The stacked gold exhibits sharp octahedral crystals with minor quartz. This specimen was found at the Harvard Mine in Tuolumne County, Calif.

The Peabody Museum brings the California Gold Rush to life by presenting historical instruments and artifacts. These include a mining pan filled with gold dust, a balance for weighing specimens, an instrument for measuring the velocity of air in mines to ensure proper ventilation, a field chemical lab called a “blowpipe kit,” and a silver candlestick decorated with mining-related symbols that miners used for illumination while underground.

“The Little Flame” is a crystallized leaf gold that weighs 13.05 troy ounces. It was found at the Eagle’s Nest Mine in Placer County, Calif.

“This is one of the finest collections of gold specimens ever put on display anywhere in the world,” said Jay Ague, the Peabody’s curator-in-charge of mineralogy and meteoritics.

“Colorado Quartz 1” measures 7.0 x 5.5 x 5.0 inches and weighs 58.68 troy ounces. The piece has gold plates on and in quartz, octahedral gold crystals and dendritic gold. Its origin is the Colorado Quartz Mine in Mariposa County, Calif.

The exhibition also gives Yale University an opportunity to remind visitors of the school's interesting connection to the California Gold Rush. Seven years before gold was discovered in the American River at Sutter’s Mill, Yale professor James Dwight Dana had completed a tour of California’s Sacramento Valley. A pioneering geologist and mineralogist, Dana identified the region as a potential source of gold, remarking that the rocks there “resemble in many parts the gold bearing rocks of other regions: but the gold, if any there be, remains to be discovered.”

The gold specimens and artifacts are on loan to the Peabody from The Mineral Trust. The collection had previously appeared at the American Museum of Natural History in New York City.

Credits: Photos by Harold Moritz, courtesy of Yale University.

N.C.-Sourced Star Rubies Could Yield a Giant Windfall for Family of Humble Rockhound

The Mountain Star Ruby Collection, a grouping of four museum-quality gemstones discovered near Asheville, N.C., by self-described rockhound Jarvis Wayne Messer, is being offered for sale by Guernsey’s in New York City. The four star rubies weigh a total of 342 carats and display six-ray asterism.

The auction house will be receiving sealed bids through June 5 and the lot could yield an eight-figure windfall for Messer's widow, family and investors.

Messer, who made his living as a fishing guide, was constantly searching for rare and unusual stones in his native Appalachia.

“I started off as a pebble pup at 6 and worked myself up to a rock hound at 13,” Messer told the Associated Press in 1994. “What began as a hobby led me to one of the finest jewels in the world.”

In 1990, while searching an ancient stream bed in a still-secret location, Messer made the unprecedented discovery of four star rubies, including the 139.43-carat Appalachian Star Ruby and the 86.54-carat Smoky Mountain Two Star Ruby, which displays distinctive stars on both the front and back of the stone.

“When I found the [Appalachian Star Ruby] I did not realize how important a stone it would become,” he said in the 1994 interview. “I knew it was a ruby and a beautiful specimen. But we did not know what we had until we started to cut the stone. I realized what we had found when I made my first cut. The star just popped right out. Right from the beginning I could see it portrayed attributes that no other stone has.”

Guernsey’s President Arlan Ettinger told The Jeweler Blog that the needles are so bright that they "look like neon."

In 1992, the Appalachian Star Ruby became a top attraction at London’s Natural History Museum, where it drew 150,000 visitors in just four weeks, according to Ettinger. The museum's press release described the gem as the "world's most impressive star ruby."

The Appalachian Star Ruby has been compared favorably to the Smithsonian’s Rosser Reeves Star Ruby, which is one carat lighter. Ettinger explained that Messer’s ruby may be superior to the Rosser Reeves because it has six prominent needles, whereas the Rosser Reeves displays only five prominent needles and one broken needle.

After the exhibition, the gem returned to North Carolina, where it rejoined the rest of the collection and languished for more than a decade.

After Messer passed away in 2008 at the age of 52, his widow and family considered selling the collection, but lacked the funds to get the proper gemological testing and documentation. With the help of friends and investors, the stones found their way to the Gemological Institute of America in August of 2011.

Appraisals of the collection have put the value between $91 million and $120 million.

When gem enthusiasts discuss the finest star rubies, they generally invoke the famed gemfields of Burma and Sri Lanka. That Messer sourced his star rubies in North Carolina makes their story that much more remarkable. The collection includes the Appalachian Star Ruby: 139.40 carats, Smokey Mountain Two-Star Ruby: 86.54 carats, Promise Star Ruby: 64.16 carats and Misty Star Ruby: 52.36 carats.

Ettinger told The Jeweler Blog that he's already gotten serious inquiries from "top museum people."

He has yet to set a pre-sale estimate for The Mountain Star Ruby Collection. The four-stone lot will have no minimum reserve.

"There is not a lot of precedence on this," he said. "They will sell for what they sell for. We will do our best."

The Sunrise Ruby currently holds the record for the most expensive ruby ever sold at auction. The 25.6-carat gem yielded $30.4 million. The most expensive gem ever sold at auction is the 59.6-carat Pink Star diamond, which had a hammer price of $71 million.

Credits: The Mountain Star Ruby Collection images courtesy of Guernsey’s.

More Deep-Earth Discoveries Locked Inside a Diamond — a 'Tiny Indestructible Spaceship'

A series of groundbreaking discoveries have the science community singing the praises of diamonds — especially the ones with inclusions. One physicist compared the precious gemstone, which can ferry material to the surface from hundreds of miles beneath the Earth's crust, to a "tiny indestructible spaceship."

A few weeks ago, we reported on a never-before-seen deep-Earth mineral — calcium silicate perovskite — that had traveled to the surface trapped within a diamond. The unstable material would have normally deformed as it moved to the surface, but within the body of diamond, it remained intact.

Then we learned about the discovery of ice-VII, a type of water ice that forms under enormous pressure. Previously, scientists theorized that ice-VII likely existed in great abundance in our solar system, but they did not think it could naturally occur on Earth. That thinking was turned upside down when traces of the unique crystallized water was found encapsulated in a diamond.

Both the calcium silicate perovskite and ice-VII originated 400 miles deep within the Earth's crust and rode to the surface in volcanic eruptions as diamond inclusions. Neither could have survived the massive pressure change outside the protection of the diamond.

“Diamond is a remarkable vessel for sampling the geochemistry of the deep mantle,” Steven Jacobsen, a mineral physicist at Northwestern University, told EOS.org, “because of its ability to seal off trapped inclusions from the reactive environment during ascent, like a tiny indestructible spaceship.”

As diamonds form hundreds of miles beneath the Earth's crust, tiny bits of their surrounding environment can be trapped inside. What's particularly unique about diamonds is that the inclusions will remain under the same pressure as they were during the time they were encapsulated.

"The diamond lattice doesn't relax much, so the volume of the inclusion remains almost constant whether it's in the Earth's mantle or in your hand," noted Oliver Tschauner, a professor of geoscience at the University of Nevada, Las Vegas.

A press release provided by the university explained that in the jewelry business, diamonds with impurities hold less value. But for Tschauner and other scientists, those impurities have infinite value, as they may hold the key to understanding the inner workings of our planet. In the most recent case, they revealed that aqueous fluids reside deeper in Earth than anyone ever expected.

The once-elusive ice-VII has 1.5 times the density of Ice-I, which is the type of ice we might put in a soft drink. Ice will progress from ice-I to ice-II, and so on, based on differing pressure and temperature conditions.

"These discoveries are important in understanding that water-rich regions in the Earth's interior can play a role in the global water budget and the movement of heat-generating radioactive elements," Tschauner said. "It's another piece of the puzzle in understanding how our planet works."

The ice-VII findings by Tschauner and his team at the University of Nevada were published in the journal Science. The findings related to the discovery of calcium silicate perovskite by scientists at the University of Alberta were published in the journal Nature.

Credit: Image of 1,109-carat Lesedi La Rona courtesy of Sotheby’s.

After 51 Years, Maasai Tribesman Who Discovered Tanzanite Finally Reaps a Financial Reward

Back in 1967, a Maasai tribesman named Jumanne Ngoma happened upon a cluster of intense blue-violet crystals in the foothills of Mount Kilimanjaro in Tanzania. At first glance, they appeared to be sapphires, but it was later revealed that the stones were a never-before-seen variation of zoisite.

The stunning mineral soon caught the attention of Tiffany & Co., which wanted to feature the gemstone in a broad-based advertising campaign. Its marketing department's first task was coming with a better name. “Blue zoisite” sounded very much like “blue suicide,” and that wouldn’t do. Instead, the gems would be called “tanzanite,” a name that would honor its country of origin.

Tiffany’s tanzanite marketing campaign transformed a once-obscure stone into the “gem of the 20th century” and, in 2002, the American Gem Trade Association chose tanzanite as a December birthstone. To this day, a 7km by 2km area in Tanzania is the only place on the earth where this type of zoisite can be found.

Despite tanzanite's commercial success, the now-78-year-old Ngoma had never reaped any financial gain from his discovery.

Via text message, Asha Ngoma made a desperate plea to Tanzanian President John Magufuli on behalf of her dad, who is ill and partially paralyzed.

On Friday, the President responded with a reward and well deserved words of praise.

"Mr. Ngoma is a veritable Tanzanian hero," Magufuli told The Citizen. "But what did he get after discovering tanzanite about 50 years ago? Nothing. Nothing at all. In fact, it is people from other countries who have benefited more from this unique gemstone."

Magufuli announced that Ngoma will be receiving 100 million shillings (about $44,000) from the Tanzanian government. The average annual salary in Tanzania is $25,922.

Prior to earning the cash reward, Ngoma had received from the Tanzanian government two certificates of recognition for his accomplishment, one in 1980 and the other in 1984. Neither came with a monetary benefit.

"We must stop this wrong habit of neglecting people who do great things for this country," Magufuli said.

The Tanzanian president announced the reward during the unveiling of a 24.5km wall, which encircles the Mirerani mining site to prevent tanzanite smuggling.

Credits: Tanzanite crystals by Rob Lavinsky, iRocks.com – [CC BY-SA 3.0], via Wikimedia Commons; Petersen Tanzanite Brooch photo by Penland/Smithsonian.

Elaborate World Series Rings Use Gemstones to Tell the Story of Astros' First-Ever Championship

The Houston Astros' 2017 World Series rings tell the story of the franchise's first-ever championship using 225 colorless diamonds, nine orange sapphires and 16 blue sapphires set in 14-karat white and yellow gold. Each ring weighs 90 grams and glitters with 10.40 carats of genuine gemstones.

Players, coaches and team management received their new bling during a special ceremony at Minute Maid Park last week.

According to the team, the top of the championship ring illustrates how — when the pieces come together — history can be made. The colorful design features the team's iconic "H" logo rendered in colorless diamonds layered over a yellow-gold-framed Texas star formed from orange sapphires. The star sits atop a circle of blue sapphires — also framed in yellow gold — which is encircled by a halo of tiny white diamonds.

The "H" posed a tricky design challenge for Minneapolis-based Jostens. The solution was to use 11 custom-cut baguette diamonds, which, not coincidentally, were the number of the team's post-season wins. Another challenge was sourcing orange sapphires of a hue that exactly matched the team colors. According to published reports, Jostens and Astros' team management had to go back and forth a number of times before getting it exactly right.

The logo's diamond halo includes 56 round diamonds, which represents the 56 years of Astros franchise history prior to earning a world championship. In all, the total diamond count for the top of the ring amounts to 112, the number of wins — both during the regular season and post season — that the Astros achieved to win the World Series.

And the symbolism continues...

On one side of the ring is the player's name rendered in raised yellow-gold lettering. Below the name is the the iconic Houston skyline, paying the ultimate respect to the city and fans who never wavered in their support for their team. A rendering of Minute Maid Park's left field wall seems to lift up the city of Houston, a sentiment expressed by many fans when describing what this championship has meant to them and their community in light of the devastating flooding that hit the city in August of 2017. Layered over the wall is the player's number encrusted in white diamonds. "Our guys were playing for something bigger than themselves," team president Reid Ryan said.

On the opposite side of the ring, the phrase "Houston Strong" is prominently displayed in contrasting yellow gold atop the year, which is rendered in diamonds. A single solitaire diamond sits in the top of the Commissioner's Trophy, representing the first World Series victory in franchise history. The trophy seems to be rising from the center of Minute Maid Park. The Roman numeral LVI sits to the right of the trophy, paying tribute to the 56-year history of the Astros franchise.

The open sides of the ring feature a rim of round colorless diamonds set in contrasting yellow gold and punctuated by two princess-cut sapphires, an orange stone on one side and a blue stone on the other. Each is set in a bezel that's shaped like a home plate. These sapphires represent Houston's unique achievement of being both American and National League Champions, a feat never accomplished by any other Major League team.

The interior of the ring showcases the results of each series in the Astros' playoff journey, including the logos of the Boston Red Sox, New York Yankees and Los Angeles Dodgers. The bottom edge is inscribed with the organization's rallying cry, "Earned History," and includes the Astros' logo rendered in black enamel on 14-karat white gold.

Jostens reported that the Astros ordered 1,322 championship rings, which were distributed to the team's players, coaches, clubhouse and training staff, baseball and business front office members, medical staff, part-time associates, Hall of Famers, owners and broadcasters.

The only team to order more were the 2016 champion Chicago Cubs. That team ordered 1,908 rings, a nod to the prior time the Cubs won the World Series — 1908.

Credits: Images via Twitter.com/Houston Astros; Courtesy of Jostens.

Music Friday: Miranda Lambert Confesses Cheating Ways to Her Engagement Ring in 'Dear Diamond'

Welcome to Music Friday when we bring you awesome songs with jewelry, gemstones or precious metals in the title or lyrics. Today, country star Miranda Lambert stares down at her engagement ring and confesses a deep, dark secret in the 2011 ballad, "Dear Diamond."

The song's protagonist has cheated on her husband and she fears that her once-flawless marriage could be torn apart.

She asks her diamond ring for clarity. If she confesses her indiscretions, she'll break his heart. If she doesn't, the guilt will haunt her.

She sings, "Dear diamond, pretty and new / Perfectly flawless, too good to be true / Dear diamond, you shine like the sun / You wrap around my finger just like he does / You cost more than he wanted to lose / And with this ring I said I do / I promise to never do what I've done / I've lied to someone."

Lambert explained the origins of the song in an interview with CMT.com. Apparently, the characters in the story are fictional.

“When you first get engaged, as the girl, you’re constantly staring at your ring, showing everybody your ring,” she told CMT.com. “I just thought it would be a cool concept to write a song to my ring. And, of course, the dark side of me just kind of leaned toward the darker version instead of going happy with it. But I think that was the right way to go.”

"Dear Diamond," which features the haunting harmonies of country and bluegrass singer, Patty Loveless, is the sixth track from Lambert's Four the Record album.

Lambert told Rolling Stone magazine that Loveless was one of her heroes and that the collaboration was really special to her — "a dream come true."

With more than one million records sold, Four the Record reached #1 on the U.S. Billboard Top Country albums chart and ascended to #3 on the U.S. Billboard 200 albums chart. It also placed as high as #12 on the Canadian Albums chart.

Born in Longview, Texas, in 1983, Lambert became interested in country music after a attending a Garth Brooks concert as a nine-year-old. Lambert made her professional singing debut with "The Texas Pride Band" while she was still in high school. She also performed with the house band at Reo Palm Isle in Longview, Texas.

In 2003, Lambert placed third in Nashville Star, country music's version of American Idol. Her first album, Kerosene, made its debut at #1 on the Billboard Top Country Albums chart. In April 2017, Lambert won the ACM Award for Female Vocalist of the Year for a record eighth consecutive year. She also has won two Grammy Awards out of 12 nominations.

Please check out the audio track of Lambert and Loveless performing "Dear Diamond." The lyrics are below if you'd like to sing along...

"Dear Diamond"
Written by Miranda Lambert. Performed by Miranda Lambert, featuring Patty Loveless.

Dear diamond, pretty and new
Perfectly flawless, too good to be true
Dear diamond, you shine like the sun
You wrap around my finger just like he does

You cost more than he wanted to lose
And with this ring I said I do
I promise to never do what I've done
I've lied to someone

Dear diamond, what will we do?
Well I like the devil, just face the truth
Dear diamond, be my saving grace
What you don't know will kill him, that I can't face

You cost more than he wanted to lose
And with this ring I said I do
I promise to never do what I've done
I've lied to someone, dear diamond

Dear diamond, with your band of gold
Some people you have, some people you hold
Dear diamond, I promise to keep
The secret I have while he's holding me

Credit: Screen capture via YouTube.com.

Impulsive 'Ace of Cakes' Star Duff Goldman Pops the Question With Ring Made From Butcher's Twine

In a rambling love treatise posted to Instagram, Ace of Cakes star Duff Goldman explained to his 197,000 followers on Monday why he proposed to girlfriend Johnna Colbry with a ring made from butcher's twine.

It turns out the 43-year-old chef can be a bit impulsive, so when the idea of popping the question to long-time girlfriend Johnna Colbry, 24, came to him like "a mule kick to the heart" on Sunday, he had to get it done right away. With no time to purchase a "real" ring, he used what he had on hand.

“I woke up yesterday and it felt like any other day," Goldman wrote on Instagram. "Sun was shining, birds was chirping. I made some coffee, ate a little breakfast, and got in the shower. I was shaving my head when like a mule kick to the heart I realized that I am absolutely in love with Johnna (@letushear) and I can’t imagine living another day without her in my life. She is kind, funny, smart, beautiful, cool, wise, and sexy. She’s a tempest of feeling.”

"I didn’t plan this out," he continued. "It just happened and it was so glaringly obvious that I couldn’t have stopped it if I wanted to. I asked her to marry me. She said yes. I cannot imagine a state of happiness that is more intense than whatever I’m feeling right now. My heart just might burst."

He then explained why he decided to use professional butcher's twine — the same material used for trussing turkeys and tying up stuffed chicken breasts — as a symbol of his devotion.

"I’m sorry I didn’t have a real ring," wrote the Food Network star. "I hope you don’t mind butcher’s twine. I am a chef, after all."

Colbry shared Goldman's photo of the couple holding hands on her own Instagram page and added this comment: “Officially my ride or die. My forever muffin. My buffalo. I’m so crazy about you @duffgoldman and I can’t wait to spend the rest of my life going on adventures with you!"

On Tuesday, Goldman told People magazine how he was overcome with emotion while shaving his head in the shower on Sunday.

"It was just like, ‘Boom! You’re incredibly in love with this girl, you need to marry her.'” he told People. “I almost called her from the shower—I think it was a good idea that I didn’t though.”

Instead, he decided to propose later that day while celebrating Easter Sunday with Colbry and her family. He even asked for her mom's blessing.

Goldman's last-minute decision to use butcher's twine as a ring is not a great leap from the material that was used as a marriage symbol thousands of years ago. Papyrus scrolls dating back 6,000 years are evidence of the exchange of braided rings of hemp or reeds between spouses. Ancient Egyptians considered the circle to be a symbol of eternity, and the ring signified the perpetual love of the spouses.

We're guessing Colbry and Goldman will be upgrading her twine ring in the near future.

Credits: Images via Instagram/Duff Goldman, Instagram/Johnna Colbry.

Four Magnificent Diamonds to Headline Sotheby's New York Auction Later This Month

Diamond lovers are in for a big treat later this month as Sotheby's New York will present an impressive array of rare gems at its Magnificent Jewels sale. Among the headliners of the April 18 event are fancy-colored diamonds in pink, orangey-pink and blue, as well as a D-flawless pear-shaped diamond weighing in excess of 33 carats.

Carrying a pre-sale estimate of $4.2 million to $5.2 million is the auction's top lot — a fancy intense pink diamond weighing 7.01 carats. The natural-color, square-cut diamond has a clarity of SI2 and is set in a simple four-prong ring.

A D-flawless, 33.25-carat pear-shaped diamond is the star of a gorgeous pendant necklace that carries a pre-sale estimate of $4 million to $5 million. The pear-shaped stone, which carries the ultra-rare Type IIa purity grade, is topped by a marquise-shaped diamond weighing approximately 1.00 carat.

A fancy intense orangey-pink diamond weighing 7.37 carats and accented by two emerald-cut diamonds is expected to fetch between $3 million and $5 million. The unusual natural-color diamond boasts a clarity of VS1 and is set in a ring that's embellished with near-colorless and pink diamonds.

Rounding out the highest-profile lots at Sotheby's is this rare fancy intense blue diamond weighing 3.47 carats. Entering the sale with a estimated price range of $2 million to $2.5 million, the cut-cornered rectangular step-cut gem is secured with four prongs on a simple white metal band.

Sotheby's New York will be hosting previews of these and many other sale items, starting on April 13.

Credits: Images courtesy of Sotheby's.