Diamond Enhancements – Part 2: Color Enhancements


Earlier we talked about treatments that enhance the clarity of diamonds and why you should probably stay away from them. Today we’re talking about the other enhancement: color treatments. These treatments are generally performed on diamonds that would receive a low color grade from the GIA. They can turn a diamond white or colorless, or if desired, can create fancy colored diamonds. Just like clarity enhancements, both the World Jewelry Confederation and the Federal Trade Commission require any color treatments to be disclosed at the time of sale. So what are these color treatments? And are they to be avoided like clarity enhanced diamonds? Let’s start with the different types of treatments. The three most common color treatments are coating, irradiation and “High Pressure, High Temperature,” or HPHT.

What is coating?

Coating is a technique that hides a less desirable diamond color with a very thin layer of chemicals. The chemical makes a yellow-tinted diamond, one that would receive a low color grade from the Gemological Institute of America, appear whiter. The color of the chemical film complements the yellowish color of the diamond, causing the two colors to cancel each other out and appear white. Usually, the film is applied to the lower section of the diamond, which makes this color treatment harder to detect if the diamond is already set in a piece of jewelry.

Color coating is basically the fracture filling of color treatments. It is an impermanent treatment that makes a diamond look better than it actually is without actually improving anything. Unlike fracture filling though, which can disappear when the diamond is exposed to jewelers’ fire or acid, color coating can sometimes disappear or chip away with soap and hot water. Yes, routine cleaning can degrade the appearance of a color-coated diamond. That’s why the GIA doesn’t grade color coated diamonds, nor will Diamond Lighthouse sell them. Buyers in the diamond industry don’t like to buy diamonds that may magically change appearance someday.

What is irradiation?

Diamonds before and after irradiation. Photo via Wikimedia Commons
Diamonds before and after irradiation. Photo via Wikimedia Commons

This treatment is fairly self-explanatory. It involves bombarding the diamond with high-energy particles that alter the diamond’s crystal lattice, meaning its atomic structure, so a color center is produced. Depending on the type of particle, this treatment can turn a diamond black, green, blue, or any mix of those colors. Irradiated diamonds can then be treated with heat to produce orange, yellow, brown or pink stones.

There’s no way, outside of a lab with highly specialized equipment, to tell the difference between an artificially irradiated diamond and a natural fancy colored diamond. Diamond irradiation is a permanent enhancement, which is why the GIA will grade them. They’ll just make sure to note that the diamond was artificially irradiated. An irradiated diamond won’t be worth nearly as much as a natural fancy-colored diamond, but it will be much easier to find. If you want a fancy colored diamond, purchasing an irradiated stone (don’t worry, they’re completely safe) is a much cheaper way to get one. Just don’t expect to get a lot of money for it if you ever choose to sell it.

What is HPHT?

High Pressure High Temperature treatment is a process introduced by General Electric in 1999. It involves taking an otherwise gem quality stone with an undesirable brown color and using special equipment to expose it to extremely high pressures and temperatures, similar to those in the earth’s mantle where the diamond was originally formed. Those conditions transform the brown-tinted diamonds into colorless or near-colorless diamonds. When this technology first came out, the jewelry industry panicked. At the time, there was no way to tell whether a diamond had been HPHT treated or not. Now, the treatment can be easily detected by a well-equipped gemological laboratory. Because it’s a permanent treatment, the GIA will grade HPHT treated diamonds, but they’ll write “HPHT Treated” prominently on the grading report. Still, buyers and dealers are wary of HPHT diamonds, worrying that their presence in the market could decrease consumer confidence in naturally colorless diamonds, which could potentially decrease their value.

Should you buy a color treated diamond?

If it’s coated, the answer is a definite “no.” Under no circumstances do you want to buy a diamond that will one day revert back to its older, less desirable color because you exposed it to too much soap and water. If it’s irradiated or HPHT treated? That’s up to you. As discussed, those treatments are permanent and the GIA will grade them. If you don’t want to spend a huge amount on a fancy-colored diamond, irradiated isn’t necessarily a bad way to go. Likewise, if you can’t afford the colorless diamond of your dreams, choosing an HPHT processed diamond will get you a great-looking stone at a much lower price. Just hope you never want to sell it.

Even though all color treatments are required to be disclosed to the buyer at the time of sale, that doesn’t always happen. Whether by mistake or just a dishonest jeweler, it’s entirely possible for the information to get lost along the way. Buyers are therefore very wary of color-treated diamonds. All it takes is one cataloging error to misrepresent an HPHT diamond as a naturally colorless one and your reputation is tarnished. There’s also the issue of valuation. It’s already difficult to determine the value of a natural fancy colored diamond due to their rarity. Irradiated diamonds confuse the issue even further.

Diamond Lighthouse does not sell color-treated diamonds. We’re able to get you more for your diamonds than you’ll find anywhere else because we’ve built a network of expert buyers and dealers who recognize a diamond’s true value. We’re able to sell your diamonds to these buyers for you because they trust our gemologists and our sales team for their honest and accurate diamond evaluations. Color treatments, whether permanent or impermanent, are a murky area in the diamond industry. Many of our buyers wouldn’t deal with us if there was even a chance they would be getting a color treated diamond. We avoid color treated diamonds so we can continue getting you the best offers for your diamond jewelry.

If you have a non-color treated diamond you’re looking to sell, Diamond Lighthouse is the only way to guarantee the best price. We can reach out to buyers and dealers who are specifically looking for diamonds like yours. And because we’re so trusted in the diamond industry, our buyers are willing to pay more for your diamonds than any pawn shop or local jeweler. With the money you earn from diamond lighthouse, you can upgrade your jewelry without having to settle for any color treatments at all.




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