Are Treated Gems "Real"?
When entering the world of colored gemstones—whether as a lapidary artist, a collector, or a jewelry buyer—you will quickly encounter the term "treatment" (or "enhancement").
A treated gem is a 100% natural stone extracted from the earth that has undergone artificial processes in a laboratory to improve its appearance (color or clarity) or durability.
The most common misconception is that a treated gem is a "fake" or synthetic gem. This is entirely false. However, because treatments alter the stone from its natural state, ethical sellers must always disclose any treatments to buyers, as treatments significantly affect the final value of the stone.
In this guide, we will break down the most common gemstone treatments you will encounter in the gem trade.
1. Heat Treatment (Thermal Enhancement)
Heat treatment is the oldest, most common, and most widely accepted gemstone enhancement in the world. It is estimated that over 90% of all rubies and sapphires on the market today have been heat-treated.
How It Works
Gemologists place dull, cloudy, or poorly colored rough stones (often called Geuda in Sri Lanka) into highly specialized, computer-controlled ceramic furnaces. The stones are heated to extreme temperatures—sometimes exceeding 1,800°C (3,300°F)—for several days.
This process essentially mimics and accelerates the natural geological conditions that formed the stone in the earth. The extreme heat causes internal chemical elements (like iron and titanium) to dissolve and mix within the crystal lattice, which can:
- Intensify or lighten the stone's color.
- Melt internal "silk" (microscopic rutile needles), drastically improving clarity.
Stability and Care
Standard heat treatment is permanent and highly stable. A heat-treated sapphire will not fade in the sun and requires no special care beyond normal jewelry maintenance.
Spotting Heat Treatment: Gemologists use microscopes to look for "altered inclusions." When a stone is heated to 1,800°C, natural crystal inclusions inside the gem often melt, explode, or form "halo" stress fractures around them. This is a dead giveaway that the stone was cooked.
2. Irradiation (Radiation Treatment)
Irradiation sounds terrifying, but it is responsible for some of the most vibrant and affordable gemstones on the market today—most notably, Blue Topaz.
In nature, blue topaz is exceptionally rare and usually very pale. The deep, electric "Swiss Blue" and "London Blue" topaz stones you see in every jewelry store do not exist like that in the ground. They start their lives as cheap, colorless, or brownish topaz.
The Process
The colorless rough is placed inside a linear accelerator or a nuclear reactor and bombarded with electrons or neutrons. This radiation alters the "color centers" (the crystal lattice structure) of the stone, turning it a deep brown. Afterward, the stone is gently heated, which turns the brown into a permanent, vibrant blue.
Is it safe to wear? Yes. While the stones are highly radioactive immediately after treatment, international regulations mandate that they be quarantined in secure, lead-lined facilities. They sit there for months or even years until their residual radiation levels drop to absolute zero. Only then are they released to lapidaries for cutting.
3. Fracture Filling and Oiling
Unlike heat or irradiation, which alter the stone at an atomic level, fracture filling is a physical treatment used to hide surface-reaching cracks. This treatment is universally associated with Emeralds.
Emeralds grow in violent geological environments and almost always contain heavy internal fractures and inclusions (affectionately called jardin, French for "garden").
The Oiling Process
After an emerald is cut and polished, lapidaries place the stone in a heated vacuum chamber filled with cedar oil or a specialized polymer resin (like Opticon). The vacuum pulls the air out of the microscopic cracks, and the pressure forces the oil deep into the stone. Because the oil has a similar refractive index to the emerald, the cracks visually disappear, making the stone look significantly clearer and greener.
Stability and Care
Unlike heat treatment, fracture filling is not permanent. If you place a fracture-filled emerald in an ultrasonic cleaner, or scrub it with harsh degreasing dish soap, you will strip the oil right out of the stone. Suddenly, a seemingly flawless gem will look cracked and cloudy.
For this reason, filled stones must only be cleaned with warm water and a soft cloth.
4. Diffusion Treatment
Diffusion is a more modern and controversial treatment, primarily used on corundum (sapphires and rubies).
Instead of just heating the stone to alter its internal chemistry, the gem is heated in a crucible filled with a foreign chemical powder—most commonly Beryllium or Titanium.
At temperatures near the melting point of the gem, the chemical powder vaporizes and actually diffuses (penetrates) into the crystal lattice of the stone. Beryllium diffusion can turn worthless, cloudy grey sapphires into stunning, highly valuable Padparadscha (pinkish-orange) colors.
The Controversy
The problem with diffusion is that it is often a shallow treatment. If a lapidary accidentally scratches a titanium-diffused blue sapphire and attempts to re-polish it, they might grind right through the blue surface layer, exposing the colorless core underneath!
Beryllium diffuses much deeper (often entirely through the stone), but because foreign chemicals were introduced, gemological laboratories classify this as an "Artificial Color Alteration", and the value of a diffused stone is a fraction of a naturally colored or simply heat-treated stone.
Conclusion: Honesty in the Lapidary Trade
As a lapidary artist, you will inevitably work with treated rough. Heating your own quartz to create citrine, or stabilizing crumbly turquoise with resin, are standard practices in the workshop.
The ethical line is drawn at the point of sale. A treated gemstone is still a beautiful marvel of the earth, but transparency is paramount. Always disclose treatments, educate your buyers, and celebrate the incredible intersection of geology and human ingenuity.