Thursday, 28 October 2021

Gem Butterflies

The incredible colours of rhodochrosite, haüyne, sphene, yogo sapphires, tanzanites, hiddenite, garnets and benitoites at the Los Angeles County Natural History Museum, in the Butterfly Broach Collection.

http://gringa-gem-news.blogspot.ca/2012_06_01_archive.html


This brooch is almost entirely set with benitoite, the California state gemstone.
A barium-titanium silicate mineral (BaTiSi3O9), benitoite is a rare mineral, crystals large enough to be cut into gemstones are found only in one location: the Dallas gem mine in San Benito County, California. An unusual geologic setting of hydrothermal veins between glaucophane schist and serpentinite created this rare mineral. Benitoite is known for its high dispersion and its vivid blue fluorescence in UV light.
Orange spessartine garnets from the Little Three mine in Ramona, California highlight this brooch, along with colorless diamonds and green tsavorite garnets from Kenya.
The multi-colored sparkle of this butterfly emanates from its green titanites (“sphene”) from Madagascar. The "fire" of titanite derives from its high dispersion and refraction. Titanite (CaTiSiO5) is a fairly common accessory mineral in igneous and metamorphic rocks, but is seldom found in size and quality suitable for gems.


This butterfly brooch brings together titanites in three different colors: green from Madagascar, brown and yellow from Pakistan.

A 13.51ct rhodocrosite (MnCO3). This mineral is very rare in jewelry. Apatite and opal cover the wings, the eyes are green chromium-rich titanite (sphene).
Pink and red spinels from Vietnam highlight this butterfly brooch. Red spinel (MgAl2O4) has long been used as an affordable alternative to ruby. Some famous historical rubies are actually red spinels. Spinel is now very popular in its own right. The eyes of the butterfly are blue jeremejevites (Al6(BO3)5(F,OH)3) from Namibia.
A 10.01-ct green hiddenite is the central piece of the brooch. Hiddenite is a green variety of the mineral spodumene (LiAl(SiO3)2) in which the color is caused by small amounts of the element. chromium. Hiddenite from North Carolina is found associated with emerald, the green variety of beryl, which also owes its color to chromium. The body of this butterfly is the world's largest faceted hiddenite.
This butterfly brooch is set with blue sapphires from Yogo Gulch, Montana. Sapphire senso stricto is the blue variety of corundum (Al2O3).

Wallace Chan

Eli Frei

Van Cleef & Arpels

Diamond and Gemstone Butterfly Brooch in 18K and Platinum.

Victorian Gemstone Butterfly Brooch

A pearl, diamond and cabochon emerald butterfly brooch by Buccellati.

A carved boulder opal butterfly brooch with diamonds and sapphires.

Cindy Chao

Fire Opal Butterfly brooch by Shaun Leane.

Anna Hu’s pair of high jewellery earrings.


Van Cleef & Arpels Papillons Butterfly blue and diamond brooch

Van Cleef & Arpels

Akiva Gil

Graff multi-cut diamond butterfly brooch 119.99 carats

Wallace Chans " Whimsical Blue" Butterfly

Monday, 25 October 2021

Blue Garnets

Garnets are a group of silicate minerals that have been used since the Bronze Age as gemstones and abrasives. All garnets possess similar physical properties and crystal forms, but differ in chemical composition. The different species are pyrope, almandine, spessartine, grossular, uvarovite and andradite.

Garnet is available in a plethora of colours and is found around the world. Rarest and most valuable of all are blue pyrope–spessartine garnets. They were discovered in 1998 in Bekily, Southern Madagascar. They are actually colour change garnets, appearing blue under fluorescent light changing to reddish-purple under incandescent light. The color change is pronounced and these rare garnets have become highly sought after by collectors.
Color change garnets are due in part to varying concentrations of vanadium and chromium. The blue-green to purple color change garnets have relatively high concentrations of vanadium and low concentrations of chromium.

Very fine, gem quality blue garnets over 10 carats are scarce and valuable.

Saturday, 23 October 2021

Graff's Pigeon Blood Ruby - $8.6M

In 2014 the 8.62-carat cushion-shaped 'Graff Ruby' ring from the collection of Dimitri Mavrommatis soared beyond estimates and set a then world auction record for a ruby at $8,600,410, as well as a record price per carat for a ruby at $997,727.

Another highlight of the evening was a natural pearl and diamond necklace that was likely once the property of Joséphine de Beauharnais, the first wife of Napoleon Bonaparte. Comprising 111 pearls, the necklace sold for $3,426,669, well above the pre-sale estimate of $800,000-$1,400,000.
In addition to the Graff Ruby, the collection included a rare 27.54-carat step-cut Kashmir sapphire with a velvety blue color that sold for $5,984,474, a world auction record for a Kashmir sapphire. It had an estimate of $3m to $6m.
A pair of sapphire, ruby and diamond earrings, by JAR. Each of circular form, pavé-set with circular-cut sapphires of various hues ranging from light pink to purplish blue, surmounted with a cage set cushion-shaped stone, one a diamond weighing 3.06 carats, the other a ruby weighing 4.89 carats. Estimate 385,000 — 670,000 CHF. Lot sold 557,000 CHF.

Monday, 18 October 2021

Tanzanite

Tanzanite is the blue/purple variety of the mineral zoisite. It was discovered in the Mererani Hills of Manyara Region in Northern Tanzania in 1967, near the city of Arusha and Mount Kilimanjaro. Naturally formed tanzanite is extremely rare. Tanzanite is noted for its remarkably strong trichroism, appearing alternately sapphire blue, violet and burgundy depending on crystal orientation.
Tanzanite is a relatively new gemstone in the world of gemology and jewelry. Since its discovery, tanzanite has sold for as little as $20 per carat and as much as $1,000 per carat or more, for gem-quality, finely coloured stones.
That price may seem like a bargain in time, as tanzanite is a one-source gemstone and that source is expected to be mined out within the next 15 to 25 years.
Pleochroic means tanzanite offers three distinct colors in three crystal directions. Tanzanite has a Mohs hardness of 6 to 7.