Gemstone Education: Rubies - Treatment

Ruby Treatments: Enhancing Beauty and Color

Both rubies and sapphires, members of the corundum family, undergo similar treatments to enhance their color and clarity. Two common methods are lattice diffusion and heat treatment, each with specific effects on the appearance and properties of these gemstones.

Lattice Diffusion

• Objective: Lattice diffusion is a treatment process where certain elements are introduced into the atomic lattice of a gemstone during heat treatment to change or enhance its color.
• Process and Elements: Initially, experiments in the 1980s focused on diffusing titanium and chromium (natural coloring agents in corundum) but met with limited success in fully penetrating the stones. A breakthrough occurred in 2003 with the introduction of beryllium diffusion. Beryllium atoms, being smaller than titanium or chromium, can penetrate the entire depth of the gemstone, even in large sapphires, effectively altering their color throughout.
• Impact on Rubies: Beryllium diffusion is capable of enhancing the color of rubies accentuating the depth and intensity of the red color.

*images courtesy of GIA. Used with permission.

Heat Treatment

• Purpose: Heat treatment is employed to alter the color and clarity of rubies.
• Effects: Heating rubies can remove any purplish hue, resulting in a purer red color. It can also dissolve silk (fine needle-like inclusions), which lightens the gemstone's color and increases its transparency. Additionally, heating can cause the recrystallization of silk inclusions, enhancing the stone’s asterism—a star-like reflective effect.

*images courtesy of GIA. Used with permission.

Considerations and Care

• Durability and Stability: While these treatments can significantly enhance the gemstone's aesthetic qualities, they may affect its durability and require specific care, particularly avoiding environments that could reverse the treatment effects, such as extreme heat or certain chemicals. However, treatments that involve extreme heat such as the majority of heat treatment and lattice diffusion, are generally considered to be permanent and stable.
• Impact on Value: Rubies that have undergone heat treatment or lattice diffusion are valued differently that untreated rubies. Within the industry, heat treatment for rubies is ubiquitous and considered to be standard. On the other hand, lattice diffusion is like heat treatment with additional color-enhancing properties, and is not considered standard. Because of this, rubies that have undergone heat treatment only are substantially more valuable than comparable looking rubies that have undergone lattice diffusion. Furthermore, rubies that are treatment free (often referred to in the trade as “No Heat”) are rare and can be highly valuable.
• Disclosure: Due to the meaningful impact on value, it is crucial for sellers to disclose these treatments to buyers. Furthermore, they can affect the gemstone's care requirements.