Yellow sapphire: description, properties and photos

The most valuable specimens of yellow sapphires are mined in the deposits of Sri Lanka, especially Ratnapura area is known, where golden sapphires are mined in alluvial deposits. There are crystals suitable for cutting among the samples obtained with bright colors and fairly large sizes. Findings of more than 100 carats of gem quality are also known. Yellow corundums are found in deposits of other countries: Burma, Thailand, Tanzania. However, compared with Ceylon sapphires, the recoverable crystals are much smaller and less attractive in color.

Yellow sapphires have been used along with other varieties of corundum since antiquity, but they were less known compared to the blue and red varieties. In ancient Vedic astrology (Jyotish Aurveda), yellow sapphire is considered a Jupiterian stone and acts as a symbol of prosperity and wealth. During the colonization years of Asian countries, yellow sapphires became popular in Europe; they are found in collections of famous jewelry houses such as Bvlgari and Cartier. Today, this gem is gaining popularity and is increasingly used in exclusive jewelry.

Like other color varieties of corundum, yellow sapphires are of interest as an object for treatment. The most valuable are unheated, not subjected to any kind of enhancement, except cutting. The classic way to obtain a more saturated color in light-colored natural samples is the thermal effect (heat treatment). Such heating is considered acceptable for corundum and is diagnosed by laboratories in a number of ways. Another fairly common method is heat treatment, accompanied by diffusion of beryllium into the stone structure. In this case, in contrast to the diffusion of titanium oxide, coloring is carried out to the full depth of the sample. This refinement method is less acceptable, although the stones can be attractive and bright. Another improvement method is improvement of clarity by filling cracks in low-quality fractured corundum with lead glass, which affects their strength, durability and beauty. These are cheap stones, which can more likely be called composite material.