As the supply of natural diamonds declines and costs rise, international jewelry brands such as Austria's Swarovski, known for crystal jewelry and accessories, and Danish jeweler Pandora, have expanded their business by using lab-grown diamonds in some styles of jewelry to attract cost-conscious consumers.

Swarovski, which dates back to 1895, has operated in China for more than 30 years. Since 2019, China has been the largest market for the brand. The brand added synthetic diamonds to its portfolio of precision-cut crystals and genuine gemstones in 2016.

That year, Swarovski launched Diama, its first lab-grown diamond line, specializing in jewelry with white synthetic diamonds, indicating a shift for the company that has traditionally sold diamond simulants.

The collection has a range of products, including rings, necklaces, bracelets and earrings, with the individual synthetic diamonds all weighing less than one carat.

"Swarovski-created diamonds are 100 percent real diamonds－equal to mined diamonds in all chemical, optical and physical ways. As such, it is a perfect arena for Swarovski to enter," the company said in a statement.

"With masterful cutting techniques, the lab-grown diamonds enjoy a remarkable level of depth and dazzle ... Swarovski-created diamonds are graded using the 4C's of clarity, color, cut and carat weight."

Another company, Lusix, an Israeli lab-grown diamond brand, recently received its first infusion of investment－$45 million from two Israeli companies, Ragnar and More Investment House.

Lusix said the cash would help it speed up its development, fueled by strong demand for premium lab-grown diamonds. The company said it plans to build a new factory in Israel that will be several times larger than its existing facility. It is expected to open in the latter half of this year, the company said.

In addition, Pandora announced in May that it would no longer sell natural diamonds, fully shifting its business to synthetic diamonds.

At the same time, sales of natural diamonds have boomed as the global economy recovers from the COVID-19 pandemic and more people are buying diamond jewelry. Last year, global diamond mining and retail operator De Beers, based in South Africa, and Russia-based Alrosa said they saw their sales of rough diamonds－those that haven't been cut, processed and polished－surge significantly.

In 2021, De Beers' sales hit $4.82 billion, up 41 percent, and Alrosa's were $4.17 billion, up 49 percent, according to their earnings reports. The two giants together accounted for more than a 60 percent share of the global rough diamond market, industry reports said.

The unit price of rough natural diamonds also increased. Last year, De Beers' price for its rough diamonds rose 13 percent to $135 per carat from a year earlier, according to the company.

"Last year, sales and volumes of rough diamonds rose due to strong demand for finished diamond products downstream. Thus, the upstream supply fell short of demand. The trend is expected to continue in the first half of this year, and the market will continue to recover," said Zhu Guangyu, a senior industry analyst.

"In the past few years, the supply of rough diamonds has declined year by year, and the COVID-19 pandemic has sped up that trend. Thus, the supply of global rough diamonds has hit a record low," Zhu said.