Fredos gems: FELDSPARS – AMAZONITE, LABRADORITE, ADVENTURINE, ORTHOCLASE, PLAGIOCLASE, OTHERS

GEMS AND GEMOLOGY

Gemology has been a fascinating hobby of mine for over 20 years, reading up “Gemstones of the World” by Walter Schumann, attending practical classes on coloured gemstones, and visiting gem mining areas. I acquired some pieces, both priced and less well known, of various colours, shapes and cuts from gem-producing areas like Burma,Sri Lanka, Thailand, Cambodia etc. These have since grown to quite a collection.

Among the 63 gems species are: traditional gemstones - corundum(sapphire,ruby), beryl (emerald,aquamarine), fancy diamond; and others - spinel, chrysoberyl(cat's eye,alexandrite), tanzanite, garnet(tsavorite, spessartite,), tourmaline(rubellite,indocolite), zircon, topaz, quartz(amethyst,citrine), chalcedony(agate,chrysoprase), feldspar(moonstone,labradorite), kyanite, peridot, kunsite, scapolite, flourite and many other lesser known gemstones. (view complete list on blog archive on the right with traditional gemstones at the bottom. click on types of interest to you.)

I'm now divesting my collection. An abbreviated description is provided below each photo, including price. Example 1: m2(size ref) tq(turquoise gem) ov(oval shape) plgnbl(pale greenish blue colour) afg ( Afghanistan country) 3.82 (carat weight) (18.7x8.5mm)(dimensions LxW) in mm) op (opaque clarity) 175 (USD 175 price) 10b30 N18(ref no and location). Example 2:"sa (type sapphire), ov(shape oval), dpbl(colour deep blue), af(origin Africa), 4.43(weight in carat), (11.3x10.2x4.6mm)dimension LxWxD, ec(clarity eyeclean), 1k(price US$1000)".

Personal viewing can be done for friends in Singapore.

Those outside Singapore, purchase can be secured via registered post upon payment in USD(or Singapore equivalent) via paypal, money/postal order, account transfer/cheque (Singapore) or other mutually agreed arrangement. Do have a look and contact me for any other details.

Happy viewing!

Tuesday, January 12, 2010

FELDSPARS – AMAZONITE, LABRADORITE, ADVENTURINE, ORTHOCLASE, PLAGIOCLASE, OTHERS

Feldspars, (German for “split field”), are divided into 2 main subgroups that produce gems: orthoclase (potassium feldspar) which includes the popular moonstone (discussed separately in an earlier post); and plagioclase (calcium to sodium feldspars). There are numerous gemstone varieties and are usually for collectors though some are faceted or cut en cabochon for jewellery. Seven types are shown below.

Amazonite – (green plagioclase feldspar), vitreous lustre, colour distribution irregular, sensitive to pressure. Named derived from the Amazon. Found in Brazil, Colorado, India etc,

g1 az ovc gsgn af 49.04(36x23x7.1)op 100 10b21 L5

h1 az ovc gn br 27.06(18.2x17.3x11.2)opu 200 10b22 M20

Labradorite (plagioclase feldspar), shows “schiller” in lustrous metallic tints, often blue and green, vitreous lustre, sensitive to pressure. Deposits in Canada (Labrador, Newfoundland), Australia, Mexico, USA etc

h3 lab ov pcblfi 14.75(20x15x8) 250 8b31 L22	h lab ov blfi 11.69(17x12.5x11.5) 200 8b31 M19
l1 lab ov gblgnfi br 8.60(15x12)si 200 8b31 M20	l2 lab ov ygngfi 7.20(15.5x11.7x5)c 200 8b31 M30

Adventurine, also called Sunstone, red or orange, metallic shiny plagioclase feldspar, named after type of glass called “a ventura” in Italian; typically red, rarely green or blue, glitter. Some display star or cat’s eye effect. Found in India, Canada, USA etc

g1 sun stov bn 46.35(24x19.1x12.8)opu 450 wb1 LR21	h2 sun stov bno ta 19.18(18.4x13.4x10.1)opu 350 8b25 M25
h3 sun ovc dppeo 13.62(18x14.7x7.7) 300 8b39 M35	l3 sun ovc o-gsh in 6.55(15.5x11.7x4.7) 200 8b39 M15
l1 sun ce dppeo ma 9.55(14.3x11.3x8.7) 200 8b39 M21	l2 sun mqc bn af 7.20(23x9.6x5)tl 100 8b39 C3
m3 sun ovc ltyo ta 2.17(9.5x7.2x4.6)tp 200 8b39 N30

Goldstone (plagioclase feldspar)- red or orange, metallic, shiny lustre, covered with gold specks, from India. Fairly similar to sunstone shown above

h2 gol ovc rd in 19.79(20x15x8) 150 8b39 L14

Blue Orthoclase transparent to opaque, blue-coloured potassium feldspar; . The ones below show blue waxy lustre and are from Uruguay and Burma.

h1 fel ovc bl bu 25.11(22x16.7x10.4)si 125 8b32 L11

h2 fel ovc bl ur 16.57(21x16x6.4)si 100 8b32 C6

Golden Orthoclase – transparent to opaque, often colourless or golden, yellow, champagne-coloured potassium feldspar; vitreous lustre. Found in Madagasscar, Burma, Kenya. The ones below are from Mexico, straw-green, transparent and faceted.

h fel ov stg mx 10.65(18x13.1x8.2)c 350 8b40 L30	l1 fel ov stg mx 9.30(16x12x8.8)ec 340 8b40 N30
l2fel ov stg mx 7.09(15.9x11.9x7.3)ec 320 8b40 N22	l fel ov stg mx 5.87(13x9x6.6)ec 300 8b40 N13