Nagi Osta
Nagi Osta, certified gemologist and appraiser, Nagi Jewelers, Stamford, Connecticut. NagiJewelers.com
Looking to buy a diamond? You now have a choice between ones formed in nature and ones manufactured in a laboratory. What’s the difference? Are these new diamonds just impressive fakes? Bottom Line Personal asked Certified Gemologist Appraiser Nagi Osta to weigh in…
In nature, diamonds form when carbon (coal) is subjected to extremely high pressure deep within the earth for a million or more years. Geological forces then expel them in volcanoes or deposit them in rivers…and miners seek them beneath the crust of the earth to access them.
In recent years, manufacturers have perfected two methods for reliably creating diamonds in the laboratory…
High pressure, high temperature (HPHT): This method closely mimics geological processes. Starting with a piece of carbon, extreme heat and pressure are applied to the carbon, forcing the formation of a diamond over the course of roughly three months.
Chemical vapor deposition (CVD): The manufacturer begins with a tiny bit of an existing diamond, called a “seed.” The seed is placed into a chamber, which is then filled with carbon-rich gas. Over the next six to 10 weeks, the gas crystallizes on the seed, layer by layer, to form the diamond.
CVD diamonds are more popular than HPHT diamonds due to the superior control over clarity, color and size…lower production costs…and environmentally-friendly process. They are better-suited for high-quality, larger gem-grade stones. And they align with modern sustainability values and have gained stronger market acceptance
Because lab-grown diamonds consist of the same materials as those found in nature, they are not “synthetic diamonds.” In fact, the physical and chemical properties of lab diamonds are the same as those of natural diamonds. Only by scanning the diamond with a special machine can even the most experienced gemologist tell the difference. The Federal Trade Commission and the diamond industry have agreed that lab-grown diamonds should be engraved with “LG” for “lab-grown” and come with a certificate number. The engraving is typically on the girdle with a serial number matching the diamond’s lab report and often accompanied by the lab’s name, such as GIA LG123456 or IGI LG123456.
Caution: There have been reported cases of perpetrators attempting to pass off lab-grown diamonds as natural by matching serial numbers, color, clarity and weights. This highlights the importance of purchasing from trusted suppliers and retailers that have the advanced machinery to thoroughly scan and verify diamonds, ensuring authenticity and peace of mind.
People who buy lab-grown diamonds may be trying to avoid gems that are morally tarnished by exploitation or conflict. But reputable American jewelers no longer deal in these “blood diamonds” or “conflict diamonds,” which are mined in war zones to fund military action, terrorism or other violent activities. Other people prefer lab-grown for environmental reasons, although the manufacturing process is highly resource-intensive and produces greenhouse gases. The most obvious advantage to lab diamonds is their price, which is only about 70% of the cost of a natural diamond.
For traditionalists, nothing can replace a natural diamond. Diamonds are valued as jewelry precisely because of their rarity and the nearly miraculous subterranean processes whereby they’re formed. From a financial perspective, natural diamonds hold their value better than lab diamonds. Because the costs of lab-grown diamonds keep falling and because these products haven’t been around for long enough to prove their staying power, most jewelers warn consumers that they will not buy back lab-grown diamonds.
