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Table of Contents

Opal Consumer Information

As provided and validated by various gemmological organizations, laboratories and the "World Jewelry Confederation CIBJO

Color

Many colours are seen in opal. Body colours can vary from white to dark blue 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

Clarity

Translucent, semi-translucent, opaque.

Cut

Opals are rarely faceted because the facet edges and junctions are prone to 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

Treatment

Play-of-Color: impregnation with oils, wax or plastic

Color: Dyeing or 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

Care

Because opals have varying degrees of water content, they are delicate – 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.

Sotheby's, NY, 09-20-2012: 18 kt. Gold, Fire Opal and Diamond Ring, Sifen Chang

Create: 17/09/2012
Last reviewed: 18/09/2012

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 and this ring features a beautiful fire opal. Fire opals are typically transparent with a red, orange or yellow body color that just glows from within – hence the name “fire opal.” Sometimes fire opal can have play-of-color, but it is difficult to tell from this imageif this gem displays the phenomenon.

Most opals are cut as cabochons or polished free-form, as seen in this ring. I love the diamond encrusted flowers that surround the opal and the use of blackened gold (perhaps black rhodium plating).

The designer, Sifen Chang, is known for her one-of-a-kind art jewels that are elegant and classic. I’ve read that she is the first living artist whose pieces are featured in the Important Jewelry auctions at Sotheby’s New York, and since 2000, Sotheby’s has auctioned more than 100 of her pieces. If this opal has play-of-color, it will be even more spectacular as well as more valuable!

18 kt. Gold, Fire Opal and Diamond Ring, Sifen Chang

Opal References in Antique Gemological Books

Opal stories, superstitions and titbits

Roman Senator Nonius outlawed over Opal

Discussion on Opal Superstition in 16th century and how they

were reinstated by Queen Victoria

Overpriced Mexican Opals for Tourists (1887)

Opal References before 1700

Georg Agricola (1652) on Opals

Nicols (1652) on Opals

Tavernier on Hungarian and Indian Opals

Albertus Magnus

Sir Isaac Newton on Opal colors

Rev. King on Pliny’s Opalus and more

Opal stories, superstitions and titbits

Roman Senator Nonius outlawed over Opal

Discussion on Opal Superstition in 16th century and how they

were reinstated by Queen Victoria

Overpriced Mexican Opals for Tourists (1887)

Opal References before 1700

Georg Agricola (1652) on Opals

Nicols (1652) on Opals

Tavernier on Hungarian and Indian Opals

Albertus Magnus

Sir Isaac Newton on Opal colors

Rev. King on Pliny’s Opalus and more