18 Karat Blackened Gold, Fire Opal and Diamond Ring, Sifen Chang Estimate: 18,000 – 22,000 USD Centered by a fire opal weighing 16.35 carats, framed by flowers set with round diamonds weighing 3.12 carats, size 6, signed with Chinese characters for Sifen Chang. With signed box. This ring just caught my eye. I love opals […]Continue reading »
Opal Consumer Information
As provided and validated by various gemmological organizations, laboratories and the "World Jewelry Confederation CIBJO"
and to black, with brown, red orange in between. In recent years, a turquoise blue and a pink opal variety, owing their colour to traces of copper, has been discovered in Peru. More recently the opal find from Welo, Nigeria show an extensive color play in “harlequin shapes”. Most commercial types: white, black, fire opal.
abrasion. Some Mexican, Peruvian and crystal opals are faceted and these tend to exhibit a sleepy, milky appearance on colourless or coloured bodycolour. Most are cut en cabochon, which avoids abrasion along stark edges and are an appropriate canvas upon which to best exhibit an opal’s play-of-colour.
smoke impregnation: this treatment causes lighter opals to look like darker, black opals, which are considered more valuable. Color: Reflective foil-backing: this treatment darkens the gem and improves play-of-colour. Not easy to detect when opal is in jewelry. Color: Black paint backing: see foil backing. Several other treatments to stabilize the gem.
especially when subjected to heat, temperature changes, changes in air pressure (such as in an airplane). Dampened soft fabrics with no abrasive or chemical additives, or a soft bristle toothbrush doused with water. Collectors prize one-piece opals (without matrix or backing) that display strong play-of-colour. Collectors look for patterns such as “harlequin,” which shows a broad flash of colours when the gem or light source is moved; “pinfire,” which exhibits tiny flashes of multi-colour patches. White opals can also show these characteristics. Contra-luz opals are also collected because of their relative rarity, and their dramatic reactions to light.