Fine Amethyst from Zambia
 |
 |
At one time amethyst was quite a rare gem, and as recently as the early 19th century it was regarded as one of the five cardinal gems, along with diamond, emerald, ruby and sapphire. The rich purple was a color connected with royalty, and amethyst also became traditional for ecclesiastical rings. Many Catholic bishops still wear amethyst rings today.
The historical amethyst mines were in Idar-Oberstein in Germany and the Ural Mountains in Russia. But amethyst's position in the gem world changed in the 19th century when huge desposits were found in the state of Minas Gerias in Brazil. Amethyst is found there in large geodes in volcanic rocks. The price of amethyst fell as a result of the large supply of South American material, and in fact it was around this time that the distinction between precious and semi-precious gems entered the lexicon, with amethyst being reclassified as semi-precious.
Over the years, amethyst has been found in other Brazlian states, as well as across the border in Uruguay. Though the South American amethyst is abundant, the quality is mainly commercial grade, due mainly to the less saturated color. In fact high quality amethyst is still fairly rare and comes mainly from Africa, especially Zambia.
Where much of the South American amethyst is a pale violet or mid-toned purple, the Zambian amethyst tends to a highly saturated deep purple, sometimes with blue or red flashes. The richer color is very much in demand for finer jewelry, so the African amethyst tends to sell for a premium price. The Zambian amethyst is such a saturated purple that some material has to be rejected as too dark, a problem that hardly ever occurs with the South American material.
Another important difference between the locations is that the African amethyst tends to be found only in smaller sizes, while the South American amethyst can be found in very large sizes, even 40 or 50 carats or more. Zambian amethyst over 10 carats is rare. Where reasonable quality amethyst from South America typically sells for about $5 per carat, the higher quality deep purple from Zambia sells for $15 to $25 per carat.
High quality amethyst was first discovered in Zambia in the 1950's. Some fine material has also been found in Namibia and Tanzania. Production is limited and often erratic. But for amethyst lovers these African gems invoke the glory days of amethyst, when the purple quartz was coveted for fine jewelry and was a favorite of royalty.
Notable Gems from the AJS Collection
This month we feature rare large stones for the collector, from our collection of fine faceted gems over 10 carats. Click on the gem photos to see the details for the gem.
|
11.09 ct Yellow Sapphire from Ceylon Natural sapphires over 10 carats are extremely rare, but of all the sapphire colors, yellow is most often found in larger sizes. This lovely lemon yellow sapphire from Ceylon is very fine -- beautifully cut, eye clean and uncomplete untreated (certifiied as unheated by GRS). See all our yellow sapphire. SOLD |
|
|
20.96 ct Rubellite Tourmaline from Nigeria Many colors of tourmaline can be found in larger sizes, but big rubellites are especially valuable. This 20.96 ct octagon is a bright, slightly orangey red. The well-executed scissor cut and the superb clarity (graded "loupe clean") really bring out the luster of this exquisite stone. Perfect for an impressive pendant. See all our rubellite tourmaline. SOLD |
|
|
12.16 ct Spessartite Garnet from Nigeria The top mandarin orange spessartite is not a gem one expects to find in large sizes. So this 12,16 ct Nigerian spessartite is a very special stone. The color is a pure intense orange, certified by GRS as "vivid orange," Perfectly cut with no trace of a window, this very clean gem displays remarkable brilliance and fire. See all our spessartite garnet. SOLD |
|
|
14.42 ct Aquamarine from Mozambique Aquamarine is one of the more affordable gems in large sizes. This 14.42 ct aqua blue cushion from Mozambique has very good saturation, and is fashioned in a portuguese cut to maximize its brilliance. This is a very clean gem (graded "almost loupe clean") at a very attractive price. See all our aquamarine. SOLD |
|
|
|
15.41 ct Morganite from Madagascar It is not that unusual to find morganite over 10 carats, but most specimens are a pale salmon pink. Recently we found two exceptional morganites from Madagascar in a pure saturated pink -- the 15.41 gem shown here, as well as a 17.50 ct cushion cut. Both are beautifully cut, very clean and completely untreated. These are among the nicest morganites we've seen in years. See all our morganite. SOLD |
|
11.45 ct Red Zircon from Tanzania There are very few fine red gems in very large sizes. This deep orange-red zircon from Tanzania displays tremendous fire, with orange and red flashes as you turn it in the light. Because zircon is a very dense material, this 11.45 ct gem is well sized for a ring, with dimensions of 13,88 x 12,25 x 7.41 mm. Completely natural and unheated. See all our red zircon. SOLD |
News from AJS and the Gems World
-
The Argyle mine in Australia is the source of 90% of the world's pink diamonds. Recently Rio Tinto discovered the largest specimen ever found in Australia, a 12.76 carat rough diamond, light pink in color. The diamond was found in October 2011 and after two months of evaluation and planning, work has started on polishing it. The diamond is being polished by Richard How Kim Kam in Perth.
The finished stone will be known as The Argyle Pink Jubilee, in honor of the Queen Elizabeth II Diamond Jubilee. There is no announcement yet on the expected yield from the material, but very large pink diamonds are extremely rare. In fact Christie's has only auctioned 18 pink diamonds over 10 cts in its 244 year history.
Ask the Gem Experts
Each month we answer questions from our customers. We welcome your questions and you can submit a question from our contact page.
Could you compare blue zircon and blue topaz? Which is the better gem for a ring? CE, USA
Zircon and topaz are fairly similar in hardness, with zircon at 7.5 and topaz at 8.0. Topaz has perfect cleavage while zircon has indistinct cleavage. But where blue zircon is a rare gem, rarely found in the commercial market, topaz is a very common stone, sold in every retail channel. All of the blue topaz in the market is treated with radiation and then heated. The more saturated colors, sometimes called "swiss blue" and "london blue," are irradiated in nuclear reactors and must be held from distribution until they are no longer radioactive. The only treatment for the blue zircon is low temperature heating. Blue zircon also has a higher refractive index and considerably more sparkle.
I noticed that the gem certificates shown on your website don't give clarity grades for any of the stones. Why is that? KRM, Australia
You will find that none of the major gemological labs -- such as GRS, GIA or AGL -- give clarity grades for colored gemstones. This is because there is no standard clarity scheme for colored gems like there is for diamonds. The reason is that different gem varieties have different clarity standards. Emerald, for example, tends to have many inclusions and even high quality emeralds will have eye-visible inclusions. Some gems, such as aquamarine, are often found nearly inclusion-free. Other gems, such as sapphire and spinel, fall somewhere in the middle. For more information on the topic see our article on Clarity Grading for Colored Gems.
All the best in gems,
Arnold, Rung & Ron
