TREATMENTS OF PRECIOUS GEMSTONES

Understand the main treatments used to enhance the appearance of stones.

sapphire

SAPPHIRES

Natural sapphires can be treated to improve their color, clarity or appearance.

Main treatments
Chauffe (Heating)

Most common. Improves color and clarity by reducing inclusions and intensifying color.

Remplissage par verre

Glass fills fractures and cavities to improve clarity. Less stable than heating. Not accepted in high-end market.

Diffusion

Surface diffusion of chemicals to modify or intensify color. Surface layer only.

Traitements spéciaux

Beryllium (Be) for yellow sapphires, combined diffusion + heating, etc.

Untreated: rare and highly sought. Untreated sapphires are rarer and more valuable. Always request a gemmological certificate.

ruby

RUBIES

Natural rubies are often treated to improve color and clarity.

Main treatments
Chauffe (Heating)

Very common. Improves color (brighter red) and clarity by reducing inclusions. Accepted by market.

Remplissage par verre (Glass filling)

Fills fractures to improve appearance. Can make the stone less durable. Not accepted in high-end market.

Diffusion

Adds chromium at surface to intensify red. Surface layer, may fade with wear.

Irradiation + Chauffe

Used to modify or intensify color, especially on pale or pinkish rubies.

Untreated: extremely rare. Untreated rubies, especially Burmese 'pigeon blood', are among the most sought-after. Always request a gemmological certificate.

emerald

EMERALDS

Emeralds almost always contain natural inclusions. Treatments aim to improve clarity and stability.

Main treatments
Huilage (Oiling)

Most common treatment. Colorless vegetable oils penetrate fissures to improve clarity. Sometimes needs renewal.

Résine / Polymère

More stable materials than oil. Improve clarity and reinforce the stone. Accepted on the market.

Imprégnation

Resins or polymers under vacuum to fill fissures and increase clarity.

Traitements spéciaux

Stabilization, purification, color enhancement (rare and specific per origin).

Untreated: very rare. Non-oiled emeralds are extremely rare and may show more visible inclusions. Always request a certificate.

Key points

Treatments are identified and noted on gemmological certificates.

Treatments do not have the same impact on the value and durability of the stone.

Transparency and information are essential to buy with confidence.

Always request a certificate from a recognized laboratory (GIA, IGI, Gübelin, SSEF...).

For detailed pricing by country of origin and by weight (carat), subscribe to Gem Price and access all complete data.

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