Which stone sparkles in the sun?

Sunstone (English Sunstone) is the commercial name of oligoclase (from the Greek oligos – “insignificant”, and clasis – “splitting, refraction”) with inclusions of the smallest “flakes” of a crystalline variety of hematite or goethite, due to which the effect of iridescence appears in the stone – special golden shine of equally oriented scales. Sunstone can also be found under the name heliolite. It was previously believed that sunstone had the property of self-luminescence. Jewelry sunstone can be transparent or translucent, golden, yellow, reddish, light orange, and much less often green and blue-green.
Heliolite is very easy to process: it is not too hard, can be cut and polished well, and has a huge variety of shades. And for all its beauty and unusualness, it is not yet very well known, so its price is relatively low, so it is an excellent option for lovers of rare and unusual gems. Place of Birth. There are deposits of sunstone in Madagascar, Tanzania, Norway, Russia, the Urals and Karelia, Norway, India, Sri Lanka, Canada and the USA.
Before the discovery of deposits in the United States, most heliolite came to market as a translucent material from India. The vast majority of Indian sunstones are brown or red-orange in color with beautiful shillerization. Indian sunstones vary greatly in quality: they can look completely unattractive, but sometimes outstanding examples are found. In addition, oligoclase cat’s eye, opaque or translucent, is mined in India. Indian sun stone Sunstone is mined in Tanzania and is nicknamed “confetti”. Quite large golden flakes of hematite sparkle against a yellow, orange or light green aquamarine background. Tanzania is almost the only source of this interesting variety, so such stones are quite expensive. Oregon Sunstone. The first deposit of sunstone in Oregon (USA) was discovered in 1980 in the east of the state. The stone immediately attracted attention with its previously unseen brick-red and delicate green hues, quickly gained popularity and was named the official stone of the state.
Oregon sunstone is notable not only for its unusual color, but also for its transparency and, due to this, the absolutely amazing effect of iridescence (also known as schillerization or aventurescence) – the reflection of light from the thinnest copper plates suspended throughout the entire volume of the stone, exploding into myriads of sparks when properly viewing angle. The color of the stone also depends on the concentration of copper – pale yellow stones contain approximately 0,002% copper, green – 0,01%, and deep red – 0,02%. Oregon deposits and a sample of sunstone. Market value assessment. It’s worth mentioning right away that the assessment is given specifically to Oregon sunstones as the most valuable, interesting and diverse samples on the market. Due to the rich palette of solar stones, their prices can fluctuate over a wide range.
The least valuable examples are opaque sunstones and stones with inclusions (often cut into cabochons) – less than $10 per carat.
Transparent, colorless stones are also not highly valued. Their estimated value is about $8 per carat.
Yellow pastel and gold stones have a higher price tag and, depending on size, can cost around $15 per carat. Large yellow and gold stones weighing up to 8 carats are offered at $30/carat, and over 8 carats are usually priced at $40/carat.
Pink and tan stones with or without schillerization typically cost up to $50 per carat depending on the presence and intensity of the effect. High quality stones over 3 carats with shillerization are usually offered at $65/carat.
Stones ranging from 1 to 3 carats in green, intense pink and red, as well as small to medium dichroic, bi-color and tri-color stones with or without shillerization are offered in the range of $50-$500 per carat – price depends on clarity and intensity, as well as distribution colors in the volume of the stone.
The bright pink-orange stones are valued at around $1800 per carat.
The second most valuable color of sunstone is pure bright red (Pure Red AAA). Prices for stones larger than 3 carats can reach up to $1700 per carat according to the Sincancas catalog, and up to $1000 according to Federman’s estimate.
But the rarest and most valuable sunstones have a bright green and deep blue-green color. Such stones are valued significantly higher than red ones – their cost ranges from $600 to $4500 per carat. Yellow jewelry stones, with their warm and noble hue, represent sunshine and the joy of life. In the world of gemstones, there are several types, each with its own unique color scheme and origin. In this article we will talk about the most popular yellow stones, their deposits, classification and cost.

Citrine

Citrine is a fourth order yellow precious stone that belongs to the quartz group. The natural gem has a pleasant yellow tint, slightly “canary-like”. A characteristic feature of this stone is its excellent transparency. The rich yellow hue of citrine, fading to orange-red, is a sign of heat treatment of the stone. In general, the majority of citrines on sale are obtained artificially. It is produced by firing smoky quartz or amethyst. When these minerals are heated to a temperature of 500° C, they acquire rich yellow shades, due to which such “citrines” reveal their artificial origin. Citrine is a fairly hard stone – 7 on the Mohs scale, which is comparable to garnet, tourmaline and amethyst. If you run it across a glass surface, it leaves a scratch. The main deposits of citrine are located in Brazil, where it is mined and processed to jewelry quality. Additionally, some citrines are also mined in other countries such as Madagascar, Myanmar and Spain. The latter are distinguished by their special transparency and play of light (dispersion). The price of citrine depends on several factors, such as its weight, cut and clarity. Citrine can have a fairly low cost compared to some other gemstones, making it available to a wide range of buyers. The cost of citrine can range from a few dollars per carat to several hundred, depending on its quality and size. The largest citrine mined to date weighs 2258 carats and is on display at the Smithsonian Institution in the USA.

Yellow topaz

Topaz is a gemstone belonging to the group of silicates, aluminum fluorosilicate. Its transparency and unique color scheme have captured the hearts of many jewelers and collectors. The main country for topaz mining is Brazil, where the largest specimens of this stone are found. However, topaz is also mined in other countries, including Germany, Ukraine and Sri Lanka. The first association that usually arises when hearing the word “topaz” is that it is a transparent blue stone. However, topazes come in a wide range of colors, from the most common colorless to a deep purple hue. The yellow shades of topaz are due to changes in the crystal lattice of the stone. The hardness of topaz on the Mohs scale is 8 points, i.e. they are second in hardness only to stones of the corundum group – rubies, sapphires, etc., and, of course, diamonds. But despite this, topazes are very fragile stones. Topazes also have a very high specific gravity, i.e. they are quite heavy. In nature, topazes are often found very pure, without impurities. Their refractive indexes are low, i.e. Cut topazes cannot sparkle like diamonds. That is why topaz is cut in such a way as to reveal its color – emerald, radiant, etc. The price of topaz depends on several factors. First, the size of the stone is critical. Large, large specimens are usually valued much higher. Secondly, the color of topaz – from light yellow to deep gold – also plays an important role in determining its value. Dark yellow shades are considered the most valuable. The purity of the stone and the quality of the cut also affect it. Topaz price options range from a few dollars per carat to several hundred. One of the most famous examples of topaz is “El Dorado” – the largest topaz in the world, found in Brazil in 1984. It weighed about 31000 carats and was valued at several million dollars. “El Dorado” embodies all the qualities of yellow topaz – its unique color, brilliance and large size.

Amber

We already have a separate article about amber. Therefore, today we will consider only the most unusual amber stones in the world, found in different parts of the world.

1. The largest amber was found on the western part of the island of Sumatra, Indonesia. It is practically opaque. The weight of this stone when discovered was about 80 kilograms, and after processing – 47,5 kg. Its age is estimated by experts at 25 million years. Now this colossus is kept in the House of Amber in Copenhagen.
2. The Natural History Museum in London houses another amber giant, this time from Burma. True, compared to the first number, it is significantly inferior in weight – “only” 15,25 kilograms. Its age is estimated at 97 million years, i.e. he saw the appearance of such animals as bees, snakes, primates. During his reign, dinosaurs became extinct.
3. But the previous sample is not the oldest. In Illinois, USA, amber about 2009 million years old was found in 320. Its structure is no different from later stones. This find contained inclusions of some plants and animals dating back to the Triassic period of geological history, and made a significant contribution to the history of evolution.
4. By the way, about inclusions. The most common of them are small flying insects and various plants. The most interesting of them was found in Canada and preserved the feathers of a flying dinosaur that lived about 120 million years ago. Such finds are valued at tens of thousands of dollars.
5. The most expensive amber containing a small frog is considered to be a stone mined in the Dominican Republic in the 90s of the last century. It is valued at 50 thousand US dollars.

Heliodor

“Gift of the Sun” is how the name of this stunningly beautiful stone is translated from Greek. Heliodor is a variety of yellow beryl. Its color palette ranges from greenish-yellow to orange-yellow. Samples of exceptional purity are the most highly prized. Most often, such stones have greenish, golden, lemon and honey yellow shades.

The luster of the stone is glassy, ​​and the hardness on the Mohs scale is 7,5-8 points, like its “relative” – emerald. This stone lends itself well to cutting and is used in almost any jewelry. In nature, it is found in the form of rectangular crystals – prisms. In rocks it is accompanied by tourmaline and topaz.

Heliodor is mined from various deposits around the world. The main supplying countries are Brazil, Russia, Ukraine, Madagascar and Namibia. In the latter, heliodorus was first discovered in 1910. One of the largest specimens was mined in Brazil – weighing 2054 carats. It is on display at the Smithsonian Institution. In Russia, stones of small size, but of high jewelry quality, are mined.

One of the amazing properties of heliodor is the ability to change color when heated. A stone heated to 400° C becomes a light blue aquamarine. True, not for long – over time the color returns and a fake is discovered.

The value of heliodor depends on its size, cut, quality and color saturation. Heliodor prices can vary widely, ranging from a few US dollars per carat to several hundred dollars for rare and high-quality examples.

Chrysoberyl

Chrysoberyl, a noble yellow stone, has a special sparkling radiance and attractiveness. Today, it is little popular. Its “closest relative,” alexandrite, is known much more due to its unique ability to radically change color, which overshadows the rest of the beryl group stones.

The hardness of chrysoberyl is 8,5 Mohs points. This means that only three gemstones beat it in this indicator: sapphire, ruby ​​and diamond. Its strong vitreous luster and excellent dispersion are highly valued.

Chrysoberyl has a very dense golden-yellow hue, which gives it a special elegance and beauty. When cut as a cabochon, chrysoberyl exhibits an amazing “cat’s eye” (opalescence) effect, in which a vertical beam of light pierces right through the stone.

Chrysoberyl gets its name from the Greek words “chrysos”, meaning “golden”, and “beryl”, describing its yellow color. Chrysoberyl deposits are found in various countries, including Madagascar, Brazil, USA, Canada, Nigeria and Russia. A particularly famous source of chrysoberyl is the so-called “Emerald Mines of the Urals” in the Sverdlovsk region, where some of the largest and purest specimens of this stone are found.

The price of chrysoberyl depends on its purity, color, transparency and quality of cut, but is still not too high, as for a gemstone. However, chrysoberyl is valued in the jewelry industry, and depending on its characteristics, the price per carat can reach several hundred or even thousands of dollars.

Sphene

When you see a faceted sphene for the first time, you may not believe your eyes – its dispersion (sparkle) is much stronger and brighter than that of a diamond. Why is this possible?

Sphene, also known as titanite, is a titanium calcium silicate. It got its name for its interesting wedge-shaped crystals, from the ancient Greek word σφήν – “wedge”.

The color range of sphene is very diverse – colorless, pink, olive, purple crystals, but most often by sphene we mean stones of a rich yellow color with a grassy tint.

In 1795, a unique event occurred. The famous German chemist Martin Klaproth discovered that sphene contains a lot of titanium, and from that moment on, the development of sphene deposits began to be aimed at extracting titanium, and only a small part of the crystals remained for jewelry purposes.

In Russia, sphene was first found in 1842 in the Ilmen Mountains. Finds of gem-quality titanite are known in Mexico and Brazil. Beautiful collectible specimens of brownish color are found in the Urals, yellow-green – in Norway, colorless and dark brown – in Switzerland, yellow and reddish – in Italy. On the Kola Peninsula there are beautiful pink and golden radiant titanites, as well as large crystals of brown and yellow titanite.

Sphene has very interesting properties that are unique to it. We have already talked about excellent dispersion. And what else? Another thing is a change in color when the position of the stone changes, also known as “pleochroism.” For example, light green stones appear almost colorless under some light sources, yellow ones create the illusion of pink-orange hues, and blue ones turn purple.

The hardness of sphene is about 5-5,5 on the Mohs scale. That is, if you have, for example, a ring with this stone, then, unfortunately, after 1-2 years, small abrasions and scratches will already be noticeable. Therefore, sphene is more suitable for jewelry that has less contact with various hard surfaces – pendants, earrings, etc.

sphalerite

The name sphalerite comes from the Greek word sphalero, which means deceitful or treacherous. The name of the mineral was given by the German mineralogist and geologist Ernst Friedrich Glocker in 1847. This hints at the different colors and appearance of the mineral, making it difficult to correctly identify which specimen is which.

One of the most notable characteristics of sphalerite is its high dispersion (0,156). In fact, the dispersion of sphalerite is more than three times higher than that of diamond, which has a dispersion of 0,044. This means that sphalerite has a remarkable “fire” (the separation of visible light into colors by refraction or diffraction). Simply put, it refers to the flashes of color visible when the sphalerite turns in the light

Sphalerite is usually cut to maximize its brilliance and can be seen in a variety of shapes such as octagons, trillions, squares, rounds and fancy shapes such as ovals, pears and cushions. Sphalerite poses a challenge to gem cutters due to its brittle strength, softness and perfect six-way cleavage.

Sphalerite is found in hydrothermal deposits and skarns and is part of polymetallic ores. It is accompanied by minerals: often galena, as well as ankerite, arsenopyrite, barite, dolomite, calcite, quartz, pyrite, fluorite, chalcopyrite

It is mined in Spain, Mexico, USA, Canada, Australia, Russia (Urals, Northern Caucasus, Eastern Transbaikalia, Primorye), Kazakhstan (Zhezkazgan), Namibia, Germany, Poland, Czech Republic. Varieties of sphalerite suitable for cutting are found in Spain (Santander) and Mexico.

Danburite

Danburite stone is a rare collectible gem; it is of interest primarily to fans of rare and unique gems. In terms of its properties, brilliance, hardness, and dispersion, it is not inferior to jewelry quartz and topaz. Only a few deposits of danburite are known, one of them is located in Russia, in the Far East.

Danburite is the mineral boron, a calcium borosilicate. This is a fairly hard mineral – 7-7,5 on the Mohs scale. It has a glass luster, and smooth polished surfaces have a diamond luster. The color palette ranges from colorless to yellow-brown, through pinkish yellow and wine yellow. Depending on the shade and weight of the stone, its cost can reach up to $240 per carat. Small colorless stones are considered the least valuable, and danburites with a pink nuance are considered the most expensive.

This mineral is found in calcareous skarns (a type of rock), which also contain quartz, garnet, rhodolite, etc. But the main deposits of danburite are marble layers. Despite its rarity, danburite is found in many countries around the world: Myanmar, Japan, Mexico, Russia, Switzerland and others. Cut specimens from Madagascar are considered the most valuable.

The main method of refining danburite is irradiation through exposure to gamma radiation. Irradiated stones are distinguished by smoky pink, brown and orange hues.

Danburite is used as jewelry inserts by Russian, American and South African jewelry brands.

Yellow diamond

This gemstone belongs to colored diamonds, therefore it is extremely rare in nature, especially those with a rich orange tint. In general, the frequency of occurrence of yellow diamonds to the total number of colored diamonds is about 60%.

Yellow diamonds have one feature – in order to be rated higher than ordinary colorless diamonds, their color must be a fancy yellow shade (Fancy Light, Fancy Dark, Fancy Vivid and others), i.e. have good tone saturation. If gemologists decide that this is not a fancy color, then such a yellowish stone goes into the “colorless” section, with low quality, and its cost is hundreds of times less. The cost of “tangerine” diamonds starts from several million dollars per carat. Inclusions do not really affect the price if they are not critical, for example, with a huge noticeable crack.

The most famous yellow diamonds:

1. Tiffany. The largest yellow diamond in the world, weighing 128,5 carats. It has 90 facets and is currently set into a bird brooch. The decoration is considered a symbol of the Tiffany House.
2. Florentine (“Austrian Yellow Diamond”, “Grand Duke of Tuscany”). Today his whereabouts are unknown, but there is information that he is in Europe. It was a light yellow stone with a greenish tint.
3. Allnutt. Fancy Vivid Yellow diamond weighing 101,3 carats. This stone is cushion cut and was sold in 1996 at Christie’s for just over $3 million. It is now part of the Smithsonian Institution’s “Brilliance of Diamonds” exhibit.
4. Sancy. A teardrop-shaped diamond, yellow-pink in color, weighing 55 carats. According to confirmed data, the history of this stone begins in the XNUMXth century. Then the French diplomat Nicolas de Sancy bought this stone in Constantinople from a Turkish jeweler. Now this diamond is in the Louvre, in the Apollo Gallery.
5. The Golden Empress. A cushion-cut yellow diamond weighing almost 133 carats. This stone is the centerpiece of the Graff necklace (pictured above), which features 31 other yellow diamonds. The exact cost of this jewelry is kept secret, but according to experts, the price of the “Golden Empress” could be more than 20 million US dollars.