The way to prove your diamonds are natural: Buy brown ones

Runsdorf bought it for $5,000, a steal for a stone of its size and quality. “It wasn’t considered precious," she said.

Today, it’s a different story. Brown diamonds are becoming a stylish and subtle alternative to colorless diamonds (also known colloquially as white diamonds). Ranging in hue from a light champagne to a rich cognac, their more earthy look is now an asset, designers and industry analysts say, distinguishing them from their lab-grown counterparts. Prices per carat have risen accordingly.

Jewelry designer Nina Runsdorf found a 65-carat brown diamond at a trade show in the early 2000s for $5,000, a steal for a stone of its size and quality. 

“I used to be able to buy something for $700, $800 a carat," said Reema Chopra, who launched her label Khepri Jewels in 2023 with a suite of brown-diamond jewelry. “Someone sent me something today, it’s $6,000 a carat."

The price of fine brown diamonds has risen more dramatically than the price of colorless or yellow diamonds in recent years, according to Paul Zimnisky, an independent diamond-industry analyst in New York City. Some categories are “up as much as 40% over the last five years," he said in an email. It’s quite the glow-up. Before they were widely appreciated for their look, brown diamonds were often used for industrial purposes; Zimnisky says that because the stones are so hard, diamonds can be used in mining and construction equipment.

The color that used to depreciate the stones is now a selling point for some designers. Brown stones blend in more against the skin, giving the effect of what Runsdorf calls “bling without being bling."

“You can wear a 20-carat brown diamond on your neck, and it’s not flashy," Chopra said.

She finds that certain types of clients are particularly drawn to brown diamonds: men and serious jewelry collectors who want something unique. She makes some designs in all-brown and all-colorless diamonds to give clients the option.

“White diamonds are always going to have their moment," Chopra said. “But the colored diamonds are for the buyer who, in my opinion, has everything and beyond, and doesn’t need to show their money."

Debra Millman, a lawyer in New York City, bought a brown diamond choker from Khepri Jewels. Though she didn’t ever consider brown diamonds before, she finds that they match her style, “rather than the white diamond that everyone sort of has and glitters a lot," she said. “I think this is more elegant."

Designer Fernando Jorge incorporates uncommon natural materials, such as petrified wood, into the jewelry for his namesake brand. In a recent collection, he used many brown diamonds in wooden bracelets and earrings. “Suppliers are struggling to keep up," he said. “I seemingly extinguished the pear-shaped brown diamonds available in India."

Jorge remembers when salt-and-pepper diamonds, which have a high number of inclusions that give them a speckled look, became popular. “There are trends in diamonds," he said. The realization gave him “freedom" to experiment.

These stones are still uncommon on the red carpet, but Runsdorf said they had experienced a boost in 2019 when Scarlett Johansson got engaged with a brown-diamond engagement ring from Taffin, set on a brown-ceramic and rose-gold band. James de Givenchy, who founded Taffin, said he had worked with brown diamonds for decades, but agreed they’re more trendy now.

“I don’t see any slowing down on brown diamonds," de Givenchy said. “Today, I’m not surprised if you see some stones with a little orange that will go to $20,000 or $25,000 a carat." He adds that because they are cheaper than colorless diamonds, manufacturers might be more willing to lose some carat weight to get a “sexy" cut.

 Fernando Jorge incorporated sculpted wood and brown diamonds into the jewelry for his namesake brand.

The brown-diamond boom could be a market response to an oversaturation of colorless diamonds, particularly ones that are lab-grown and therefore much less expensive. “For some consumers, brown diamonds are perceived as a way to show that your diamond is natural," Zimnisky said. Rising prices may be related to the closure of the Argyle mine in Australia, which was known for its pink and brown stones.

While lab-grown diamonds may come in fancy colors like pink and blue, brown is not popular. “If we get requests, we’ll accommodate, but it’s not something we want to invest in," said Ria Papasifakis, chief operating officer at Ritani, an online retailer specializing in engagement rings.

Ultimately, it’s hard for even the pros to tell the difference between a lab-grown and natural diamond. “I can’t tell the difference unless they send it to a lab, that’s the truth," Chopra said. “A lot of wealthy people were buying colored diamonds to say ‘I have money and this is the real thing.’"

Write to Sarah Spellings at sarah.spellings@wsj.com