Gemstones and Treatments

When you admire the brilliance of a ruby or the glow of an emerald, it’s easy to forget that many gemstones have undergone treatments—processes used to enhance their appearance, clarity, colour, or durability. While these enhancements can make gems more attractive, they also affect value, care requirements, and may influence your purchasing decision.

Here's a closer look at the most common gemstone treatments and what they mean for buyers.

Common Gemstone Treatments

Heating
One of the oldest and most widely used treatments, heating is employed to enhance the colour and clarity of gems such as sapphires, rubies, and amethysts. This process mimics natural heat conditions deep in the earth.

Dyeing
Dyeing enhances or changes the colour of a gemstone by soaking it in a coloured solution. Pearls, jade, and coral are often dyed to produce more vivid hues. However, dyed colours may fade over time and should always be disclosed at the time of sale.

Coating
Some gemstones are coated with a thin layer of material to enhance colour or surface lustre. This is more common with lower-cost gems or fashion jewellery, and the coatings may wear off with time.

Fracture Filling
Fracture filling involves injecting a gem with glass, resin, or other materials to fill internal cracks or inclusions. This is frequently seen in rubies and diamonds, where the treatment improves visual clarity.

Oiling
Primarily used on emeralds, oiling involves filling surface-reaching fractures with oils to improve clarity. Since oil can dry out or be removed during cleaning, this treatment often requires maintenance.

Why Gemstone Treatments Should Matter to You

When you think about buying a gemstone, you’re likely dazzled by sparkle, colour, and cut, but beneath that surface beauty lies an important question: Has this gem been treated—and if so, how? Understanding gemstone treatments isn't just a concern for high-end collectors—it matters directly to you, the buyer. This is why being informed about gemstone treatments is crucial.

Value: What Are You Really Paying For?

Treated gemstones can look just as stunning as their untreated counterparts—sometimes even more so. But there's a catch: treated gems often carry significantly lower value than untreated ones of similar appearance.

For example, a natural, untreated ruby with a rich red colour can fetch tens of thousands of dollars per carat, while a heat-treated or glass-filled ruby with the same appearance might cost a fraction of that. If you're unaware of the treatment history, you might end up overpaying.

Knowing whether a gemstone has been treated allows you to understand what you’re paying for, and whether the price aligns with the stone’s true market value.

Stability and Care: Will It Last?

Not all treatments are created equal. Some, like heat treatment in sapphires and rubies, are stable and permanent. Others, such as oiling in emeralds or dyeing in turquoise, can fade, leak, or degrade over time.

This has real-world consequences:

• A heat-treated sapphire can withstand everyday wear and even cleaning solutions.
• A dyed turquoise, on the other hand, might change colour with exposure to sunlight, sweat, or household chemicals.

By knowing how your gemstone was treated, you can make informed decisions about how to wear it and care for it, ensuring it stays beautiful for years.

Jewellers are required to disclose most treatments a gemstone has undergone. Why? Because without full disclosure, you’re not buying with informed consent.

Imagine buying what you think is a flawless diamond, only to later discover it’s fracture-filled and vulnerable to heat or UV exposure.

Understanding gemstone treatments empowers buyers to make informed, confident decisions.

Gemstones are nature’s dazzling miracles—cut, polished, and often treated to shine even brighter. However, these treatments can lead to unexpected mishaps. Here are some stories from the unpredictable world of gemstone treatments gone wrong.

Fracture-Filled Diamonds Meet the Nail Salon

You’d think the hardest substance on Earth could survive a manicure. Fracture-filled diamonds—those injected with a clear substance to hide internal cracks—can be surprisingly delicate. One woman experienced this firsthand when her routine gel manicure turned into an unintentional experiment. Her engagement ring changed colour mid-treatment due to prolonged exposure to the UV lamp used to cure gel nails, which altered the filler’s refractive index, making it look cloudy or slightly iridescent. Diamonds may be forever, but filler isn’t.

Exploding Rubies at 30,000 Feet

Glass-filled rubies, enhanced to appear clearer and redder, are notorious for being pressure-sensitive. In one incident, a newlywed’s ruby ring, a wedding gift, suddenly cracked while flying over the Atlantic. While cabin pressure didn’t affect her champagne glass, it was more than enough to rupture the unstable filler inside the ruby.

The Turquoise That Cried, Sunscreen!

Turquoise is often stabilised with resin to prevent crumbling, but issues can arise. One beachgoer found her turquoise bracelet leaking a blue-green substance on a sunny afternoon. Her coconut-scented SPF 50 didn’t agree with the resin filler, causing it to break down under the sun, saltwater, and lotion. The result? Her wrist looked like it had been visited by a melting Smurf.

The “Bleeding” Emerald

Emeralds are frequently treated with oils or polymers to reduce the appearance of inclusions. After exposure to hot lights, one stone began exuding a sticky greenish oil from its fissures, showcasing how enhancement can lead to a meltdown.

The Colour-Changing Sapphire Sauna Surprise

Heat-treated sapphires are common, but some diffusion-treated sapphires can surprise their wearers in steamy situations. One man wearing a bright blue diffusion-treated sapphire found it faded significantly after several sauna sessions. Heat and moisture worked their way into the stone, dulling its artificially enhanced colour.

So, What Can You Do?

Ironically, treatments aimed at enhancing gemstone durability can also introduce vulnerabilities. From UV sensitivity to pressure fragility and chemical incompatibilities, these enhanced stones can act like high-maintenance husbands rather than rugged wonders.

Always inquire whether a gem has been treated and how. If treated, avoid exposing it to heat, chemicals, or pressure changes. If unsure, seek advice from an NCJV Registered Valuer™.