Color Change

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alex1 alex2

Alexandrite is a semi-precious gemstone rating 120/1000. Good examples quite rare. It was named after the Russian tsar Alexander and shows both red and green. Brazil and Sri Lanka are other sources of alexandrite. Green or bluish-green in daylight, alexandrite turns a soft shade of red, purplish-red or raspberry red in incandescent light. It differs from other chrysoberyl in that it not only contains iron and titanium, but also chromium as a major impurity. Alexandrite’s dramatic color change is sometimes described as “emerald by day, ruby by night.” The more distinct the change of color, the more valuable the stone. Best cut shape is regular. Best depth is ideal or fine. Worst is shallow with large window. Best clarity is 'clear' which is the most rare. Alexandrite is not free from external flaws . Natural Alexandrite (as opposed to the synthetic) typically have inclusions which can be better seen under magnification. Normal inclusions can include tiny crystals that look like black spots. Size of gem exponential to price. Alexandrite Is used in rings, broaches, necklaces etc. usually of silver, white gold or gold ( 17ct. + gold). Look particularly for more moden items with clear diamond settings. Gem value: please submit your form.

MARKET NEWS:
Collector's gemstone. Good quality rare and expensive even the smaller sizes. Fire is the required price marker - the more the better. Also the greater the color change the better. Not many loose stones seen as supply is usually to the top markets in Europe and Hong Kong.

colchgarnet1 colchgarnet2

Color change garnet is a semi-precious gemstone rating 220/1000. Any gem that changes color is a rare find and a treat for collectors. Garnets exhibit the widest variety of color changes in the gem world, with almost every hue exhibited. Color change garnets are mostly pyrope and spessartite in composition. Except for the color change, they are identical in properties to the Malaia variety. Their primary source is Africa. The color change is primarily from cool colors(blues, purples etc.) in daylight to warm colors (reds, orange) in artificial and bright light. The more distinct the change of color, the more valuable the stone. Best cut shape is regular. Best depth is ideal or fine. Worst is shallow with large window. Best clarity is 'clear' which is the most rare. Color-change garnet is a type II clarity stone. Stones sometimes contains rutile, apatite and pyrite mineral inclusions and intersecting needles.. Size of gem exponential to price. Color change garnet Is used in rings, broaches, necklaces etc. usually of silver or gold ( 17ct. + gold). Look particularly for more modern items with clear sapphire or zircon settings. Gem value: please submit your form.

MARKET NEWS:
Mostly all color change gems are expensive if the color change is startling. This specially applies here as generally speaking the color change in garnet is not as great as other color change gems. Most supplies from Africa with individual stones offered. A lot are badly cut to maximize size as the offerings are small.

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Color change sapphire is a semi-precious gemstone rating 110/1000. Any gem that changes color is a rare find and a treat for collectors. Sapphire exhibit a wide variety of color changes in the gem world, with almost every hue exhibited. The typical color change is from green/blue to red/violet. Trace amounts of elements such as iron, titanium, chromium, copper, or magnesium present during formation are responsible for the color of a sapphire. Chromium impurities in corundum yield a pink hue. The color change is primarily from cool colors(blues, purples etc.) in daylight to warm colors (reds, orange) in articicial and bright light. The more distinct the change of colour, the more valuable the stone. Best cut shape is regular. Best depth is ideal or fine. Worst is shallow with large window. Best clarity is 'clear' which is the most rare. Unlike ruby, color change sapphire typically occurs with excellent transparency and with very few inclusions, so it is often eye-clean. Most color change sapphire gemstones are quite small, but larger stones can be found with excellent clarity. Size of gem exponential to price. Color change sapphire Is used in rings, broaches, necklaces etc. usually of silver or gold ( 17ct. + gold) but more commonly is used as a support gem in a fancy ring or pendant. Gem value: please submit your form.

MARKET NEWS:
The amount of color change can be small to large with sapphire. More so than most gems ... and more colors. Generally you pay for the quality and grade you want. Light blue to pink is the most common. Always carry a flashlight when buying color change gems, or any other for that matter as some brokers may be unaware of exactly what they are carrying. Good buys can be had with the less than one carat color change sapphire. Make good support gems for jewelry.

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Tanzanite is a semi-precious gemstone rating 450/1000. Rare - large stones very rare. Tanzanite is the blue/violet variety of the mineral zoisite. It was discovered in the Mererani Hills of Manyara Region in Northern Tanzania in 1967 Tanzanite is noted for its remarkably strong color, appearing alternately sapphire blue, violet and purple. Tanzanite can also appear differently when viewed under alternate lighting conditions. The blues appear more evident when subjected to fluorescent light and the violet hues can be seen readily when viewed under incandescent illumination. Tanzanite is usually a reddish brown in its rough state, requiring artificial heat treatment to bring out the blue violet of the stone. A small amount of tanzanite in the marketplace has a blue color that was produced naturally through the heat of metamorphism without any treatment by people. This naturally blue, untreated tanzanite is held in very high regard by some gemstone and jewelry buyers who seek it out when making a purchase. Best cut shape is regular with most stones cut oval or emerald. Best depth is ideal or fine. Worst is shallow with large window. Tanzanite has terrific 'fire' depending on cut. Some dull specimens especially those of light shades. Best clarity is 'clear' which is the most common. Tanzanite is usually free from external flaws . Much of the tanzanite sold for jewelry has inclusions that can be seen only under magnification, so any eye-visible inclusions cause a drop in value. Also, any inclusions that might pose durability problems, such as fractures, lower tanzanite value greatly. Almost any price you care to name is being asked - and paid! - for tanzanite of top quality and large size. Tanzanite stands out in jewelry displays because most stones have a distinct hint of purple or violet in their color. People who have experience looking at gems and pay attention to color will quickly notice tanzanite in a display case of blue gems. Mostly used in gold or white gold rings with diamond surrounds. Small gems for earings etc. Gem value: please submit your form.

MARKET NEWS:
Becoming more and more popular for Middle Eastern buyers. High prices paid for large bright blue/purple loose gemstones. Supplies do not look like expanding so prices should. Not so valuable are the pale blue variety and smaller stones. All cuts available.

Double Reflective

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Zircon is a semi-precious gemstone rating 550/1000. Fairly common. Zircon exist in a wide range of colors, but the most expensive stones are deep blue, purple, red and orange. White zircons are also valuable, probably due to their extremely high 'diamond-like' refracting properties. Poor specimens too light or pastel colors. Best depth is ideal or fine. Worst is shallow with large window. Zircon has great 'fire'. Some dull specimens especially those badly cut. Best clarity is 'clear' which is the most common. Zircon is very brittle so care is needed in handling. Brownish stones from Cambodia are usually heated to obtain an intense blue color. Heat treatment is common for yellowish stones, with light blue or colorless stones being subjected to x-ray treatment and heating. Internal inclusions are usually rare. Clean crystals are common. Size of gem exponential to price. Zircon will usually be in many settings of many stones such as rings, necklaces and broaches. Prices subject to noticeable variation due to fashion trends on local markets. Usually of white or yellow gold. Look particularly for rings in clear gem 'closed' settings due to the fragile nature of the gem. Gem value: please submit your form.

MARKET NEWS:
Cambodia main supply for Asian markets. Most blue stones irradiated and the most expensive. All colors available however with some honey colored gems becoming popular. Green less popular than blue. Best blue/green zircon cut 'deep' and others emerald or variety cut. Hazardous gem for cutters and treaters however beautiful the result.

sphene1 sphene2

Titanite or sphene is a semi-precious gemstone rating 320/1000. Sphene is a brilliant yellowish-green or green gemstone of high luster, unique color shades and, with brilliant cut and an intensive fire that can compete with any other gemstone including diamond. Sphene is also known as "titanite" due to its titanium content. They are yellow, orange or green gems with many gradations between those colors. ... Sphene is found primarily in Madagascar, Mexico, Canada and, historically, in Austria. Sphene is one of the few minerals with a dispersion higher than diamond. The dispersion of diamond is 0.044, while the dispersion of sphene is 0.051. Specimens of sphene with high clarity can display a strong, colorful fire when light is passed through them. Sphene is very rare in clean stones over 5-10 carat. Even a 5-carat flawless gem is considered a rare and fine stone. Best cut shape is regular. Best depth is ideal . Worst is shallow with large window. The high birefringence usually makes some doubling of facet images visible within the stone giving it a degree of internal fuzziness similar to that often seen in zircon or peridot. A rare variety termed chrome sphene is colored by chromium and is an intense green. This gem is somewhat risky as a jewelry stone due to its softness and brittleness, but beautiful if set protectively and worn occasionally. Shield this gem from knocks, heat and exposure to acids; do not clean with steam or ultrasonics, and it will be a spectacular addition to your gemstone collection or jewelry case. Size of gem exponential to price. Gem value: please submit your form.

MARKET NEWS:
A favorite of mine. Spectacular presence under artifical light. Best gems are the light yellow colored that transform into a violent kaleidoscope. The darker brown no so good. Great for jewelry. Supply not regular. Cutting important.

peridot1 peidot2

Peridot is a semi-precious gemstone rating 840/1000. Quite common. Best variety mostly from Burma or Kashmir. Best color is a vivid leaf green. Poor specimens too light and too dull. Best cut shape is regular. Best depth is ideal or fine. Worst is shallow with large window. Peridot is quite strongly doubly reflective and has less 'fire' than most other similar gems. Best cut in round or oval. Best clarity is 'clear' which is fairly common. Large specimens not rare. Peridot is a little soft and therefore not free from external flaws . Internal inclusions are many and usually needles, light and dark spots. Less value if infused with oil, wax or resins and hardened to enhance appearance. Size of gem exponential to price. Peridot is usually larger than ruby and much less expensive, It will be used in rings, broaches, necklaces etc. usually of silver, white gold or gold (9 to 17ct. gold). Look particularly for more modern items with clear sapphire settings. Gem value: please submit your form.

MARKET NEWS:
Good supply from Asia and for those who like the forest green color in jewelry will pay good prices. Most offerings have medium fire and are clean. Others can be purchased in packets. Generally not expensive.

Select Multi-color

ametrine1 ametrine2

Ametrine is a semi-precious gemstone rating 950/1000. Ametrine is a naturally occurring variety of quartz. It is a mixture of amethyst and citrine with zones of purple and yellow or orange. Almost all commercially available ametrine is mined only in Bolivia. The color of the zones visible within ametrine are due to differing oxidation states of iron within the crystal. The different oxidation states occur due to there being a temperature gradient across the crystal during its formation. Best common shape is oval or cushion although any regular cut is OK. Any gem over a carat is rare. Best depth is ideal. Worst is shallow. Most ametrine in the low price segment can be assumed to stem from synthetic material. Since 1994, a Russian laboratory has perfected the industrial production of bicolored quartz crystals that are later irradiated to bring out the typical ametrine colors. Green-yellow or golden-blue ametrine does not exist naturally. Fine ametrine shows medium dark to moderately strong orange, and vivid to strong purple or violetish purple. Larger gems, usually those over 5 carats, tend to show the most intensely saturated hues. Dealers look for an attractive half-and-half distribution of each color, with a sharp boundary between the two colors at the center of the fashioned gemstone. Best clarity is clear. Size of gem exponential to price. Cutters sometimes fashion ametrine as mixed cuts or brilliant cuts and use internal reflections to mingle the amethyst and citrine colors. Ametrine is also popular in free-form or fantasy cuts. Gem value: please submit your form.

MARKET NEWS:
Was a lot about some years ago but not seen recently. Emerald cut for jewelry the most sought after although some stand alone purple gems are popular for those that like that color. Smaller sizes can be purchased in packets with set carat price.

watermelon1 watermelon2

Watermelon tourmaline is a semi-precious gemstone rating 470/1000. The watermelon tourmaline is a rare variety that displays three different colors in the same crystal - green (the skin of the watermelon), pink (the sweet fruit) and red the center.Tourmaline is strongly pleochroic, which means that it can show different colors in different crystal directions. In addition, many tourmalines absorb more light down the length of the crystal than across it. So a crystal that appears pale green across its length can be very dark green—sometimes almost black—when you look down its length. Best common shape is rectangular or cushion although any regular cut is OK. Any gem over a carat is rare. Best depth is ideal. Worst is shallow. The most typical inclusions resemble thread-like cavities that run parallel to the length of the crystal. Under magnification, you can see that they’re filled with liquid or gas bubbles. Growth tubes—long hollow tubes often capped with minute mineral crystals—are also common tourmaline inclusions. Dealers usually tolerate red tourmaline with some eye-visible inclusions as long as the color is strong and attractive. Inclusions that reach the surface interfere with luster and polish and make gems harder to sell. And although liquid inclusions are less visible in stones of intense color, stones with prominent whitish inclusions—no matter how vibrant the color—are undesirable. Size of gem exponential to price. Cutters sometimes fashion watermelon tourmaline as mixed cuts or brilliant cuts and use internal reflections to mingle the colors. Gem value: please submit your form.

MARKET NEWS:
A popular gem if the colors are strong enough. As a color transition gem in a large crystal they are often very included. The clean ones are rare. Often purchased for pendant and broaches. Look for deep red/green with good balance.

multitourn multitourm1

Multi-Color Tourmaline other than watermelon tourmaline is a semi-precious gemstone rating 760/1000. Fairly common. Best color is a pure hues of many colors (yellows, blues, pale pinks). Poor specimens too dark or too light. Sometimes heated to improve color. Best cut shape is regular. Best depth is ideal or fine. Worst is shallow with large window. Tourmaline has good 'fire' depending on cut. Some dull specimens especially those of dark shades. Best clarity is 'clear' which is the most common. Tourmaline is usually free from external flaws . Internal inclusions are usually needles, color banding, crackling, light and dark discoloration. Less value if heat treated. Size of gem exponential to price. Tri and bi-colored Tourmaline is usually average size and will be used in rings, broaches, necklaces etc. usually of silver, white gold or gold (9 to 17ct. gold). Look particularly for more modern items with clear sapphire settings. Gem value: please submit your form.

MARKET NEWS:
A carnival gem that largely depends on variety of colors and shapes as tourmaline can be cut in many different ways. Look for fire and presence with a regular cut.

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