- CULTURED PEARLS
- SEMI PRECIOUS GEMS
- PRECIOUS GEMS
- GEMSTONE BEADS
- PYRAMIDS & WANDS
Regardless of source, blue agate is chiefly valued for its translucency and purity of hue. The general mine run of stones from California and Namibia tend toward a slightly gray, medium-toned blue hue, sort of a stormy-sky blue. In this system of evaluation, gray, along with brown, are not regarded as hues but are treated as saturation modifiers which, when present, dull or muddy the saturation or mask the intensity of the hue. A gray mask is nearly always present in blue agate. Like a dirty film on a window, gray dulls the hue, reducing the saturation or brightness of the color. The gray may be difficult to detect but pure hues are always vivid, so the presence of gray may be inferred from a cool dullish blue. Obviously, the brighter the blue the better the stone.
Purple is the normal secondary hue, and when it is present, adds dramatically to the beauty and price of the stone. Holley blue is famous for its amethystine secondary hue, but a hint of purple can also be found in damsonite and even in stones from other locations. Occasionally a stone will be found that has a purple primary hue, but these are exceedingly rare. Stones of this color will have a blue secondary hue; that is, they will be bluish purple rather than purplish blue. The market prefers bluish purple, purplish blue, and grayish blue, in that order. The greater the percentage of purple and the smaller the percentage of gray the better the stone. I have seen only three examples of a pure blue hue without measurable gray.
Navneet gems and minerals is a supplier of Blue Agates in wholesale, a type of a chalcedony which is a semi precious stone.Posted on Thursday, December 1, 2011 - 10:47
Like many another gemstone, blue agate is marketed under a variety of aliases: damsonite, Mojave blue, and Holley blue agate are the most common. All are chalcedony from a variety of locales, with some small differences based on color and transparency of the agate.
Mojave blue is a trade name describing a slightly grayish blue opaque to semi-translucent stone found in the Mojave Desert, about a hundred miles south of Los Angeles. A similar quality material is found in Namibia. Damsonite is an opaque violetish material found in central Arizona. Holley blue is an opaque to translucent, purplish or amethystine-hued variety that has been found in and around Sweet Home, Oregon, and was named, apparently, for the Holley School near one of the sites. Another variation, Ellensburg blue, is found as glacial till scattered about the Washington state township from which it draws its name. Ellensburg blue agate often has purer blue hue.
Navneet Gems and Minerals is a wholesale supplier of Chalcedony, and especially a supplier of Blue Agate.Posted on Thursday, December 1, 2011 - 10:42
Carnelian was one of the most sought after gems of antiquity. The Egyptians, Sumerians, Hittites, Babylonians, and Mycenaeans adored this gemstone. The Roman historian pliny said that “among the ancients there was no precious stone in more common use.” A majority of classical Greek and Roman seal stones were carved in carnelian or in sard, which is another name for the brownish-orange darker-toned material. Sardonyx refers to chalcedony with alternating bands or reinforcements of white and orange that was favored for the making of beads.
The ancients differentiated between five types of sardion. Of first importance was the translucent male “blood red” stone; second came the paler yellowish orange, which was considered female. Third was the darker-toned brownish orange that we call sard. The fourth classification included agate with alternating layers or stripes of brownish orange and white, and fifth was blood-red stripes alternating with white. The first three types were found in all the best tombs.
Hue, saturation, tone
Regarding the components of color hue, saturation, and tone the modern value system almost mirrors the ancient. The dark red hue is still the most desired, although it is difficult to find a true blood red. Almost all carnelians will show some evidence of an orange secondary hue. Most of the fine carnelian beads unearthed from the royal tombs at Ur are actually a medium to dark orange to reddish orange. Thus, the finest quality might be described as a medium to dark tone (seventy to eighty percent) red primary hue (eighty to ninety percent) with an orange secondary hue (ten to twenty percent). Carnelian can also occur in a medium-toned (fifty-five to sixty-five percent) highly saturated visually pure orange hue. Highly saturated stones of this hue are at least as desirable as the so-called blood reds.
As with all chalcedony, diaphaneity plays a defining role in the quality equation. An orange stone with good crystal is more desirable than a red stone that is opaque. Crystal is the first C of connoisseurship in the evaluation of carnelian. Recently some medium-toned (sixty percent) highly translucent orange carnelian has come on the market. This material, reportedly from southern Africa, has been nicknamed “citrus agate” due to its pure orange primary hue and its high degree of translucency. Stones of this description will command the highest prices, despite the fact they are not red or even reddish.
Most of the carnelian currently on the market has been heat treated. Since ancient times, chalcedony has been subjected to heat treatment in order to create carnelian. Under magnification, natural color carnelian will usually show evidence of the thin bands called fortification, even in stones that seem uniformly colored to the naked eye; heat treatment will burn out the bands. Acid treatment produces a dark, dense, “burnt” look in carnelian. Treated stones are less translucent than natural gems.
Most of the gems currently available are heat treated or enhanced in some fashion. Much of the material available at low cost, in calibrated sizes, is undoubtedly treated. Calibrated stones are cut to precise proportions, e.g., round stones are precisely 5mm,6mm; ovals, cushions, emerald cuts, and pear shapes will be exactly 7x5, 8x6mm, etc. The aficionado should always be suspicious of calibrated stones.
The rarity factor
The real challenge may be in finding natural stones. The same problem is encountered with turquoise. Fine natural carnelian is available; however, it’s much easier to treat low-grade material than to bother with the natural. This reflects one of the ruling dynamics of the mass market: that which can be reduced to a commodity will be reduced to a commodity. Natural gemstones are inconvenient because they don’t occur in precisely uniform color, shapes, and sizes. This unfortunate tendency can only be accelerated by the coming of the computer age.
Distortions in the market can work for the connoisseur. Noncalibrated stones, those without precise measurements in millimeters, may be available at reduced prices. Natural carnelian can often be bought at a better price in carvings. If the collector is attentive, a gem of exceptional quality often can be picked from mixed lots of uncalibrated gems at a lower price than those found in calibrated parcels.
Original articles written by Navneet Gems and Minerals, a supplier of Carnelian and other Chalcedony Gemstones.Posted on Tuesday, November 15, 2011 - 12:46
Ironstone is the normal inclusion found in chrysoprase. However, with the relative abundance of material, chrysoprase is normally cut flawless. Stones from Western Australia will sometime show small black dendritic inclusions. Any visible inclusions disqualify the stone from being considered top quality.
Chrysoprase, like gem chrysocolla, has a reputation for drying out and fading when exposed to heat or a dry environment. This is certainly true for material from older European sources, chiefly Silesia. This seems not to be the case with material found in Australia; gems from New Marlborough and Yerilla are stable. However, it is still advisable to keep chrysoprase away from long-term exposure to direct sunlight and other forms of extreme heat.
The rarity factor
Since the start of the new millennium, high quality chrysoprase has been available in quantity and at very low prices. I learned long ago that abundance in gemstone is will-o’-the-wisp here today, gone tomorrow! Whenever a large deposit of any gemstone is found, the material floods the market, temporarily reducing prices. The operative word here is temporarily! Deposits, even large ones, are quickly depleted. A successful collector is an accomplished opportunist and should not be put off by a relatively low price. A fine example of chrysoprase is well worth collecting.
Navneet Gems and Minerals is a supplier of Wholesale Chrysoprase Gemstone, a type of Chalcedony.Posted on Tuesday, November 15, 2011 - 12:33
Given a consistent hue, saturation, and tone, the relative degree of translucency defines the quality grades in chrysoprase the more translucent the material the higher the price. In fact it can be said that crystal is really the first C of connoisseurship in grading not only chrysoprase but also the other varieties of agate discussed in this section. Translucency tends to decrease with size. The finest qualities of chrysoprase are often compared to jadeite. Chrysoprase, however never achieves the transparency of jadeite. Chrysoprase possesses a milky crystal, a characteristic of even the most translucent specimens. The finest jadeite exhibits a crisp, clean, limpid green hue.Posted on Tuesday, November 15, 2011 - 12:28
Chrysoprase is a Semi precious stone as it comes under the category Chalcedony, which itself is a Semi precious stone. The finest chrysoprase is usually described as apple green. It is sometime called imperial chrysoprase, an obvious attempt at a comparison to jadeite. It is a vivid visually pure green between sixty-five and seventy percent tone. The material from Marlborough Creek normally ranges from a visually pure green to a slightly bluish green. Gems from Yerilla may show a yellowish secondary hue. This yellowish secondary hue is considered a fault. Gemstones with even the slightest trace of a visible yellow secondary hue are far less desirable.
Gray is the normal mask or saturation modifier in the Semi precious gem, chrysoprase. The best of the Australian material shows no gray at all and can be best described as a vivid apple green. The general run of chrysoprase from these two sources is remarkably consistent in hue, saturation, and tone.
Another variety called lemon chrysoprase is found in Western Australia. It is a pale opaque lime green color and is actually not a chalcedony at all but a nickeloan magnesite.Posted on Thursday, November 10, 2011 - 12:42
Chrysoprase (Semi precious stone) is a green chalcedony that owes its “apple green” color to the presence of trace amounts of pimelite, a type of nickel. Chrysoprase is very close-grained microcrystalline quartz.
Two sources of chrysoprase were discovered recently in Australia, each producing, in substantial quantities, most of the material available in the market today. The first and most important source was a vast deposit found in 1965 at Marlborough Creek, Queensland. The second was unearthed in Western Australia in the Yerilla District in 1992. Material from Marlborough Cheek shows the purest green hue and is the finer of the two. Other sources include Brazil, and Kazakhstan in Central Asia, a legendary find, much of which later was determined to be green opal. Opal of a similar color is often associated with chrysoprase. In earlier times it was referred to as chrysopal.
Writting Original articles by Navneet Gems and Minerals, the source of Gem Chrysoprase, Chalcedony and other Semi precious and Precious gemstones.Posted on Thursday, November 10, 2011 - 12:25
Malachite and drusy quartz are the usual inclusions found in gem chrysocolla. Though technically inclusions, either can add to the beauty of a cut gemstone.
Inclusions and value
Drusy, tiny colorless quartz crystals growing on the gem, are the most sought after inclusions in gem chrysocolla. Although perfection in all characteristics tends to be the way the finest gems are defined, the aficionado should be alert to pleasing compositions of gem chrysocolla juxtaposed with inclusions of drusy quartz. Malachite, since it is green, is a less desirable inclusion, though it can show a pleasing juxtaposition of color and pattern in a vivid blue gem. It is the skill and sensitivity of the cutter that makes all the difference is such cases.
The rarity factor
Gem chrysocolla with the qualities discussed above is extremely rare. I might find one fine piece every few years. If a fine piece is on offer, the aficionado must be prepared to accept the price, or not have a second opportunity for many years.
Writting Original articles by Navneet Gems and Minerals, the source of Gem Chrysocolla, Chalcedony and other Semi precious and Precious gemstones.Posted on Tuesday, November 8, 2011 - 11:33
Crystal in Gem Chrysocolla
Given the consistency of hue, saturation, and tone, it is the degree of transparency that defines the various grades of gem chrysocolla. This gem is never completely transparent; it is translucent. It is the degree of translucency that is the defining factor. The greater the translucency the more the gem will be seen to glow in the light. It can be said that crystal is really the first C of connoisseurship in gem chrysocolla, as well as in the other agate varieties to be discussed in this section. Visually pure blues with a high degree of translucency is more desirable than an opaque pure blue.
Gem chrysocolla is often cut in freeform (nonsymmetrical) shapes. Shape has little effect on value except that the more interesting freeforms may command a premium. Particularly translucent gems will some-times be faceted.
Writting Original articles by Navneet Gems and Minerals, the source of Wholesale Gem Chrysocolla, and other Chalcedony Gemstones, and Semiprecious and Precious Gemstones.Posted on Tuesday, November 8, 2011 - 11:22
It is estimated that over eighty percent of gem chrysocolla is subject to a degree of color fading when exposed to a dry environment. This is particularly true of the Mexican material. As the stone dries out, the translucency and the color saturation of the gem are both diminished. According to Chris Boyd, a dealer who spends summers in upstate New York and winters in Arizona, and who has worked with gem chrysocolla for many years, fading is an issue in areas with an average relative humidity below fifty-five percent. His stone looks much better in New York than in the Arizona desert. Fading can be reversed when the gem is rehydrated by directly exposing it to moisture or to a moist environment for a short period of time.
Writting Original articles by Navneet Gems and Minerals, the source of Wholesale Non-color fading and fading Chrysocolla, both.Posted on Monday, November 7, 2011 - 13:03