Roskin Gem News Report

Sotheby’s Color Spectacular

Changing it Up

Is this some kind of record for the number of color change gems in one auction? Nine?

The Hong Kong Important Jewels July 12 auction listed Color Change sapphire, Color Change chrysoberyl, and 1 fabulous Color Change spinel, as well as a very rare Color Change diamond!

Here in this post, Changing It Up, we want to review so many jewels that feature Color Change gems! As many as there were in one auction (9), one might incorrectly assume that these phenomenal gems are common place. They are not!

Three of the nine Color Change gems did not sell, including: 1. The rare 3.43 carat cushion shape violet to purple Color Change spinel, 2. and two alexandrite (color change chrysoberyls) pairs of earrings.

SOLD

The six jewels that did sell were very impressive: two Color Change sapphire rings, two Color Change alexandrite rings, the chameleon diamond, and one – the double phenomena gem – a Color Change alexandrite cat’s-eye ring.

Two in One!

The alexandrite cat’s-eye ring, set with one oval cat’s-eye alexandrite (Color Change chrysoberyl) weighing 5.05 carats.

Estimated to sell for 400,000 – 550,000 HKD, sold for 444,500 HKD (approximately $57,000)

Accompanied by AGL report no. CS 51686, dated 15 October 2012, stating that the alexandrite is of Brazilian origin, with no evidence of enhancements and treatments, and the degree of color change is prominent with strong strength of cat’s eye. 

Brazilian Color Change

This particular Cat’s-eye Alexandrite is a slightly deep green-blue under fluorescent light, and reddish purple under incandescent light, of strong saturation, with typical natural inclusions, few surface reaching, with minor nicks and abrasions as examined under 10x magnification.

The Cat’s-eye is sharp, centered, a bit wavy, and complete.

To have both Change of Color and a Cat’s-eye in such fine quality is extremely rare. – gr

The Chameleon

A diamond ring, set with a pear-shaped Fancy Deep Brownish Greenish Yellow diamond weighing 2.01 carats, framed by brilliant-cut diamonds, to the pear-shaped diamond surround, mounted in 18 karat white gold.

Fancy Deep Brownish Greenish Yellow Diamond – Chameleon
Having two modifying colors, brownish and greenish, should give the gemologist a clue that something unusual might be going on here. Check the fluorescence. According to the report, this diamond fluoresces strong white.

Accompanied by GIA report no. 6441787529, dated 3 November 2022, stating that the 2.01 carat diamond is Fancy Deep Brownish Greenish Yellow, Natural Colour, VS2 Clarity.

Why “Chameleon”?

According to the GIA Diamond Grading Report, “the color of this stone changes temporarily when gently heated, or when left in darkness for a period of time and is known in the trade as “CHAMELEON”.

According to the report, this diamond fluoresces “strong white.” While this is very unusual for most diamonds, it is not surprising for a Chameleon.

Chameleons are not only known for their unusual fluorescence (see under ultraviolet light), they also typically show a strong phosphorescence (a glow after you remove the ultraviolet light). Most, if not all, Chameleon diamonds will phosphoresce a very strong yellow. It is quite possible that this type of unusual phosphorescence led gemologists to examine more closely these unusual diamonds to discover the Chameleon color change.

Having seen several Chameleon diamonds, it is likely that this diamond changes from a Fancy Deep Yellow (not graded by GIA) to a Fancy Deep Brownish Greenish Yellow (graded in its stable position). While we base this on experience, there is no guarantee that this Chameleon is like all others.

Estimated to sell somewhere between 80,000 – 120,000 HKD, the 2-carat Chameleon Diamond sold for 215,900 HKD (approximately $28,000 USD).

Color Change Sapphire, emerald and diamond ring – Lot 340

Set with an oval Colour-Change sapphire (blue to purple) weighing 13.22 carats, bordered by cabochon emeralds, to the brilliant-cut diamond surround and shoulders decorated with circular-cut sapphires, mounted in 18 karat white gold.

Accompanied by an AGL report no. 8089057, dated 11 March 2019, stating that the colour-change sapphire is of Ceylon origin, with no gemmological evidence of heat and no clarity enhancement.

Estimated to sell between 120,000 – 180,000 HKD. Sold for 228,600 HKD (approximately just under $30,000 USD)

Color Change Sapphire and diamond ring – Lot 267

Set with a step-cut Colour-Change sapphire (changing blue to purple) weighing 12.45 carats, flanked by trapeze-shaped diamonds, mounted in 18 karat white gold.

Accompanied by SSEF report no. 124099, dated 16 August 2022, stating that the colour-change sapphire is of Ceylon origin, with no indications of heating, and with a moderate colour-change. Further accompanied by two GIA dossiers no. 6435598313 and 7433598375, dated 10 June 2022 and 9 June 2022 respectively, stating that the 0.37 and 0.36 carat diamonds are F and D Colour, both VS1 Clarity.

Alexandrite and diamond ring – Lot 265

Set with an oval alexandrite weighing 2.17 carats (changing bluish green to reddish purple), framed by brilliant-cut diamonds, to the oval and brilliant-cut diamond surround and brilliant-cut diamond bifurcated shoulders, mounted in platinum. 

Estimated to sell for somewhere between 150,000 – 250,000 HKD. Sold for 215,900 HKD (approximately $28,000)

Accompanied by SSEF report no. 108062, stating that the alexandrite is of Brazilian origin, with no indications of treatment. 

Tap here to see the full results of the latest Sotheby’s Hong Kong Auction.

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