Colors of stones and metals and engraving

MARIO UBOLDI Jewellery Art crafts all designs in 18k gold (yellow, red and white) or 925 silver. A finer quality can be offered upon request. As a principle of honesty, all our jewelry is manufactured in the same, solid metal; what is on the outside, is in the inside.

During our design process, we define the metal along with the matching stones. However, we understand that there are different preferences. The below list indicates the spectrum of colored, natural stones, we usually work with. Please feel free to customize your jewelry within this range. 

Furthermore, your jewelry may be personalized with an engraving such as a name, a quote, a date or a special occasion. A personal message makes your jewelry even more unique.


Amethyst is a transparent purple quartz. Origin of name from the Greek -amethystos- "not drunken". Amethyst was considered to be a strong antidote against drunkenness. Greek legend tells the story of a maiden Amethystos who was pursued a drunken god called Dionysus. She prayed to the goddess Artemis to remain chaste. The goddess granted her prayer, transforming her into a white stone. Filled with remorse Dionysus cried tears of wine over the stone turning it purple.
Different localities can produce a unique amethyst to that particular region or even to that particular mine. It is mined in Brazil, Uruguay, Bolivia and Argentina, Zambia, Namibia and other African countries. Very dark amethyst, mostly in small sizes, is also mined in Australia.
Color: the color range varies from pale lilac to deep purple.
Hardness: 7

Aquamarine belongs to the gemstone family of Beryls. Origin of name Latin "aqua"meaning water and "mar"sea. Legend has it that Mermaids tails were made of aquamarine. Aquamarine is usually free of inclusions and possesses a superior brilliance. The more intense the colour of an Aquamarine, the higher its value.The principle supply of aquamarine stones comes from Brazil, Russia, Afghanistan, India and Pakistan
Color: pale blue to light greenish
Hardness: 7.5-8

Citrine is a form of quartz with ferric iron impurities and is rarely found naturally. Origin of name from the French word "citron" meaning lemon. Also called citrine quartz. Most commercial citrine is in fact heat treated amethyst or smoky quartz. Brazil is the leading producer of naturally mined citrine.
Color: the different shades range from yellow, gold, orange brown shades of transparent quartz.
N.B. Citrine and Amethyst are the exact same minerals, the only difference is the level of oxidation of the iron contained in the mineral. As this can be done artificially by heat or irradiation a large majority of Citrine sold today is heat treated amethyst. There are currently no scientific ways to determine if Citrine was changed artificially.

Diamonds are a form of carbon. Origin of name: From Greek for invincible. A diamond is a crystal completely made of the element carbon, except for trace impurities like boron and nitrogen. The arrangement of the carbon atoms or its crystal structure within the diamond gives it its unique properties. As well as being the hardest known material, it is also the least compressible, and the stiffest material, the best thermal conductor with an extremely low thermal expansion, chemically inert to most acids and alkalis, immensely strong, rigid structure with a very high melting point (3800°C) diamond is the hardest known natural substance. Diamonds are found in Africa (Angola, Botswana, South Africa, Congo, Zimbabwe, Tanzania), Asia (Russia and India), North America (Canada and USA) and Oceania (Australia)

Color: it is rare to find diamonds are truly colorless.
Hardness: 10.00

Read more about diamonds

Diamonds come in all colors but these natural Fancy Color Diamonds are rare and can be very expensive. One out of 10,000 normal diamonds is a fancy color diamond. The color of a fancy colored diamond is measured differently to a normal diamonds. The grading scale is based on the intensity of the color.

Emerald is a valuable Beryl that owes its color to chromium or vanadium, which make it the bright green. Origin of name emerald is said to be a Sanskrit word meaning green (Sanskrit is a classical language of India). Emeralds can have many inclusions and flaws so can be brittle and liable to break.The value of an emerald depends on cut, colour, clarity and carat. Clear stones with vibrant colour command the highest prices. It is found in Brazil, Pakistan, Russia, East Africa, India, Madagascar and Columbia, at this point in time the best emeralds come from Colombia.
Color: Emeralds come in many shades of green and bluish green.
Hardness: 7.5-8
N.B. Many emeralds are treated to hide surface-reaching breaks and improve transparency.

Garnets are nesosilicates. 0rigin of name: from ancient Greeks as colour reminded them of the pomegranate seed or granatum. Garnets do not show cleavage (the tendency of crystalline materials to split along definite planes, creating smooth surfaces) so when they fracture under stress, sharp irregular pieces are formed. Because the chemical composition of garnet varies, the atomic bonds in some species are stronger than in others. The harder species are often used for abrasive purposes. It is found in the regions of Kenya, Sri Lanka, Thailand, Brazil, India, Madagascar, Canada, USA, Czech Republic and Spain.
Color: virtually all colors
Hardness: 6-7.5

Jasper is microcrystalline quartz and is made from very small grains, it is a semi-translucent to opaque. Jasper has been used for thousands of years as tools and weapons during prehistoric times and for ornaments and jewelry later. Origin of name from the Greek iaspis. Jasper is commonly found in the regions of North Africa, Sicily, France, India, Venezuela and Germany, USA etc.
Color: dark green,yellow, brown, green, yellow, red and white.
Hardness: 6.5 to 7.5

Lapis Lazuli is an opaque to translucent precious gemstone composed mainly of lazurite and calcite. Origin of name from the Persian "lazhward", which was the name of a place in modern Turkestan known for its deposits of lapis lazuli (“stone of lazhward”). The finest colour is intense blue, lightly dusted with small flecks of golden pyrite. Polished Lapis can be made into jewellery. In the past it was also ground and processed to make the pigment Ultramarine for tempera paint and oil paint.
Color: Deep azure blue to light blue, bluish green
Hardness: 5.5-6

Moonstone is the best known gem variety of orthoclase feldspar. It is usually polished as a cabochon. Its importance as a gemstone arises because of adularescence, a floating light effect and sheen, compared to the light of the moon. This phenomena results from alternating layers of two kinds of feldspar,which cause light to scatter. Moonstone specimens commonly exhibit chatoyancy (a mobile, wavering striped reflection), and sometimes display a strong cat's eye.
Color: most desirable color of moonstone is blue, but it also occurs in grey, white, pink, green and brown.
Hardness: 6 to 6.5  

Onyx is a chalcedony that occurs in bands of different colors. Onyx refers to a black and white banded variety of Agate and brown varieties are named Sardonyx. It is composed of relatively straight, parallel layers of different colors. This structure lends itself to cameo making.
It is usually cut into cabochon, or into beads, and is also used for intaglios and cameos. Some onyx is natural but much is produced by the staining of agate. It is available in the regions of USA, Germany, Brazil, Mexico, India, and Africa.
Hardness: 7

Opal is a type of quartz. Origin of name: from Sanskrit (Sanskrit is a classical Indian language) upala = precious stone. They are luminous and iridescent with inclusions of many colors. Opals show a play-of-color (a shifting of spectral colors) Opals are found in the regions of Mexico, Brazil, USA, Japan, Honduras, Kenya, Czechoslovakia, Peru, Canada but by far Australia is the main source of opals, almost ninety-five per cent of all fine opals come from the dry and remote outback deserts.
Color: White, black, red, orange, most of the full spectrum, colorless, iridescent. Very infrequently of a singular color.
Hardness: 5.5- 6.5

Pearl is a smooth, lustrous, chiefly calcium carbonate organic gemstones. Natural pearls are nearly 100% nacre, a protective mother of pearl coating that is secreted to protect the organism for a foreign body that has entered the shell. Natural or real pearls come mainly from oysters, although there are other bi-valve molluscs which can produce them. Almost any species of bivalve or gastropod is capable of producing pearls. However, only a few species, such as the famous pearl oysters, can create pearls which are highly prized. Cultured pearls are produced by artificially introducing a foreign object into the fleshy part of oysters, which become coated with nacre in a similar manner to natural pearls. Imitation pearls, simulated pearls, have been produced for many years. Pearls are found in the regions of Japan, China, Tahiti, Australia, Indonesia, Philippines, USA and Burma.
Color: white or cream, but the color can vary according to the natural color of the nacre in the various species of mollusc used. Can also be black or various pastel shades. Pearls (especially freshwater pearls) can be dyed yellow, green, blue, brown, pink, purple, or black
Hardness: 3.5 to 4.0
N.B.To test if a pearl is natural, rub across the edge of your teeth; real pearl feels rough, simulated feel smooth.

Peridot is the gem quality variety of the mineral olivine. Origin of name either the Arabic word faridat meaning "gem" or the French word peritot meaning "unclear". Peridot is one of the few gem stones that come in only one color. The depth of green depends on how much iron is contained in the crystal structure. It is found in the USA, Myanmar, Egypt, China, Sri Lanka and Pakistan.
Color: varies from yellow-green to olive to brownish green.
Hardness: 6.5 - 7

Quartz is a crystalline rock or mineral composed of silicon dioxide. Quartz is the second most common mineral in the Earth's continental crust and found in all types of geological environment. There are 49 variety's, a number of which are gemstones, some of which are very beautiful and very rare. Origin of name from Saxon word Querkluftertz = cross-vein ore.
Color: colorless, white, gray, yellow to brown to black, violet, pink
Hardness: 7

Ruby is the red variety of the mineral called Corundum which is composed of aluminium oxide (any other color of corundrum is a sapphire, see below). The red colour is caused mainly by chromium and titanium. It is natural for rubies to have imperfections in them, including colour impurities and inclusions of rutile needles known as "silk. Origin of name comes from ruber, Latin for red. Some rubies show a 3-point or 6-point star or asterism. These rubies are cut into cabochons to display this effect. Natural occurring rubies are very rare and extremely rare in large sizes over 3 carats. They can be found in many regions around the world from India, to East Africa, to South America, the Hindu Kush and a few deposits in the United States.
Color: pinkish red or deep, rich red color
Hardness: 9
N.B. Almost all rubies today are treated in some form (of which heat treatment is the most common practice) and rubies which are completely untreated and still of excellent quality command a large premium. Improvements used include color alteration, improving transparency by dissolving rutile inclusions, healing of fractures (cracks) or even completely filling them.

Sapphire is any color of the mineral corundum other than red, those are called ruby (see above), corundum is composed of aluminium oxide. Sapphires tend to be translucent or transparent and have high amounts of refraction. The most desirable sapphires are generally those with an intense blue color with plenty of sparkle and life. Various shades of blue result from titanium and iron substitutions in the aluminium oxide crystal lattice. Some sapphires show a 3-point or 6-point star or asterism. These sapphires are cut into cabochons to display this effect. They can be found in Brazil, Tanzania, Sri Lanka, Kashmir, Thailand, Madagascar and Australia. 
Color: Shades of blue.
Hardness: 9

Sapphires are mainly known for their shades of blues, but they come in an assortment of colors.
Color: all colors across the spectrum including white and black.
Hardness: 9
N.B. It should be noted that many Sapphires can be treated to enhance or change their color. They are heated or irradiated to produce stronger colors such as greens, yellows or even blues. While the color of Sapphires can be changed by intense heat and radiation, it is stable for daily wear jewelry.

Spinels are composed of magnesium aluminium oxide. Most Spinel is formed due to intense heat from volcanic activity or hydrothermal underwater streams. Origin of name: from Latin spinella meaning little thorn, after crystal shape. Spinels next to ruby and the rare red diamond, is the most expensive of all red gems. With a hardness of 8 and no cleavage planes, natural spinel is a tough and durable gemstone suitable for any kind of jewelry. Unfortunately most Spinel that is sold commercially is synthetic. Sri Lanka, Brazil, Thailand, and United States are most notable sources of natural spinel.
Color: cobalt blue, red to blue to mauve. Dark green, brown, black-green, pink, deep pink with an orange tinge.
Hardness: 8

Tanzanite is part of the zoisite mineral species and is only found in East Africa. Discovered in 1967 in the Umba Valley near the Usambara Mts. in Tanzania. Tanzanite may be colorless, yellow-green, brown, or blue to violet when found; the crystals are heat treated to enhance their color.
Color: Tanzanite is noted for its remarkably strong trichroism, appearing alternately sapphire blue, violet, and sage-green depending on crystal orientation. (Trichroism is the property possessed by certain minerals of exhibiting three different colors when viewed from three different directions under white lights. However, most tanzanite is subjected to artificial heat treatment to improve its colour and this significantly subdues its trichroism.
Hardness: 6.5
N.B: Tanzanite is a brittle stone and although it can be worn daily, care should be taken to protect it from knocks, pressure and extreme temperature changes. Do not use a home ultrasonic to clean jewelry with tanzanite

Tsavorite is one of two green varieties of garnet, though arguably the more important of the two. Especially in smaller sizes, tsavorite creates competition for emerald because it is less included, rarely treated, and more durable. Like some emerald and green tourmaline, tsavorite garnet owes its green hues to the presence of vanadium and chromium.First discovered in Tanzania in 1967 and a few years later in Kenya, tsavorite's name pays homage to the nearby Tsavo National Park.
Color: Green in all shades, from light to dark
Harndess: 6.5 to 7.5

Topaz is a fluorosilicate and can contain trace elements that cause different colors within the Topaz. Origin of name: from Greek Topazion, a Red Sea Island often covered in mist. Topaz wasn't really known about before the classical era, in the Middle Ages the name topaz was used to refer to any yellow gemstone. Deposits of topaz are found in the regions of Russia, Siberia, Brazil, Sri Lanka, Africa and China, Japan, Pakistan, Myanmar, Nigeria, Australia, Mexico, and in the United States.
Color: Varies in a broad range of: yellow, blue, pink, peach, gold, green, red, and brown.
Hardness: 8
N.B. Topaz is often heated to change or enhance it's color.

Tourmaline is one on the most complex gemstones of the silicate group and there are 10 different varieties created by the dozen or more elements they contain. Origin of name: from Sinhalese turamali = stone of mixed colours. There are Tourmalines, which change the color from daylight to artificial light and others display chattoyance(a mobile, wavering striped reflection).Tourmaline is found in Africa, Brazil, Madagascar, Mexico, Myanmar, Namibia, Sri Lanka and USA.
Color: depending on the variety green, red to pink, light to dark blue, colorless, purple , neon blue, brown, black, red to green and green to red.
N.B. Tourmaline may be heated to enhance it's color.

Tigers Eye is mainly composed of silicon dioxide, it is a form of quartz that acquires fine golden lustre when polished. Origin of name: the stone resembles the eye of a tiger. Tiger's eye is a semi precious stone with a rich yellow and golden brown stripes that display chattoyance(a mobile, wavering striped reflection). Tigers eye is found in regions of South Africa and Western Australia.

Turquoise is composed of aluminium phosphate and copper. Origin of name: from French for Turkish stone as in ancient days it was transported through Turkey. It was very popular during the days of Ancient Egypt and Ancient Persia and known to man since at least 6,000 BC. Delicate veining, caused by impurities, is desired by some collectors as proof of a natural stone. Turquoise is found in the regions of Iran, southwestern United States, Africa, Australia, Tibet, China, Siberia and Europe.
Color: Blue, blue-green, green
Hardness: 5-6


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