Dinny Hall Gemstone Guide
Agate is a semi-precious gemstone found all over the world and comes in a huge array of colours, some natural and some dyed. Agate ranges in opacity from almost transparent to opaque. Chalcedony, carnelian, black onyx, chrysophrase, jasper and tiger’s eye are all types of agate.
Almandine is a fine burgundy garnet with high lustre. Deposits can be found in Madagascar, Burma, Brazil and the USA. See garnet.
Amethyst is a quartz gemstone found in shades of purple, ranging from intense violet purple, to subtle pink-lilac. It can also be found in shades of green and rose pink, though harder to find. Amethyst is the birthstone for February.
Andalusite is found mainly in Sri Lanka and Brazil though it is named after the Andalusia region of Spain. Andalusite varies in colour from pale yellow brown to dark bottle green. This beautiful iridescent stone shows flashes of yellow, green and red when it catches the light.
Apatite is a lustrous bright blue gemstone. Apatite is a delicate stone, but it is coveted for its vibrant colour. Sources include Burma, Sri Lanka, Russia and Canada.
Aquamarine is a variety of beryl. Its finest colour is that of a stunning clear blue sea, though it can vary from a pale greeny blue to an intense blue. Aquamarine is principally found in Brazil and Madagascar, but other sources include India, Burma and the USA. Aquamarine is the birthstone for March
Beryl is a family of gemstones. Those with a distinct colour are given a specific name, including, emerald (green), aquamarine (sea blue), chrysoberyl (yellow, green), alexandrite (green with flashes of red) and morganite (pink). There are many beautiful shades in between which are simply known as a particular colour beryl, for example, green beryl and red beryl. ***
Blue topaz is the most popular of the topaz family. The blues come in a spectrum of shades from pale aqua to a deep, rich blue. Topaz is skilfully heated or irradiated to achieve these beautiful colours, natural blue topaz is quite rare. Our blue topaz mainly comes from the USA, though it is also found in Brazil, Sri Lanka and Burma.
Citrine is a quartz gemstone found in shades of lemon, yellow, orange and sherry colours, sometimes referred to as lemon quartz. Most Citrine is from Brazil. Citrine is the birthstone for November.
Chrysoberyl ranges in colour from pale lemon, soft lime to strong mustard greens. Found in Burma, Brazil and Sri Lanka. Chrysoberyl is a type of beryl.
Diamond is composed of pure carbon. The purest white and the purest clarity together with the best-cut are the most desired though they can occur in an amazing variety of spectacular colours including yellow, pink, blue and shades of cinnamon, cognac and chocolate. Along with rock crystal, diamond is the birthstone for April.
Emerald is the most precious form of beryl and is a distinctive green colour, though rarely flawless they are highly sought after. Found in granite and alluvial deposits, the finest emeralds are from South America and Africa. Emerald is the birthstone for May.
Garnet is a family of gemstones coming in a spectacular array of rich colours. Ranging from semi-precious to precious, red garnet is the most common. Almandine garnet is much more rare and is prized for its lustrous colour. Rhodolite garnet is very similar to Almandine. To the untrained eye it can be difficult to tell them apart. Tsavorite garnet is a rich intense green and is considered a precious garnet as it is less commonly found than the red tones. Garnet is the birthstone for January.
Hematite is a gunmetal coloured stone with a metallic lustre, composed of iron oxide. It is most commonly used to make beads and set into silver jewellery. Found all over the world and in 2003 was discovered on Mars.
Iolite was named after a Greek word for Violet though is comes in a wide spectrum of blue shades. It is commonly found in Madagascar, Burma, and India.
Kyanite is a pale to deep blue gemstone, not unlike a good iolite in appearance. From the same family as andalusite, deposits are found in Burma, Brazil and Kenya.
Kunzite was first discovered in 1902 by a gemologist called Kunz in North Carolina. It has a distinctive lilac pink colour and can be cut into very large stones. In fact, this stone is at its most beautiful when over 10ct in size.
Labradorite is a feldspar gemstone, meaning a stone that is found scattered not far beneath the earth’s surface. The distinctive iridescence and flashes of metallic blues, greens, golds and bronzes are created by light interplaying with the internal structures within the stone. It is named after the Labrador Peninsula in Canada where it is found, but also occurs in Russia, Norway, Finland and India.
Lapis Lazuli, the finest gem quality stones are intense blue sometimes with a dusting of golden pyrite and are highly prized, though can be found in great abundance. Sources include Afghanistan, Russia, Chile, the USA and Canada.
Lemon quartz is fresh citrus yellow in colour - see quartz.
Moonstone is an opalescent gemstone found in shades of white, green, grey or rainbow - which as it suggests, reflects all different colours. It is a feldspar meaning it is formed in rocks near the Earth’s surface. The most important sources are found in Burma, Sri Lanka and India. Moonstone, along with pearls, are the birthstone for June.
Morganite is in the beryl family and sometimes referred to as a pink aquamarine. It is most commonly found in a pale shade of delicate pink, though can be peachy and even a violet pink. Morganite is found most commonly in Mozambique and Zimbabwe.
Onyx is part of the agate family and has been used in jewellery since ancient times, most commonly in beads, silver jewellery and small sculptured objects. Onyx can be brown, white or black in colour – see agate.
Opals are one of the most fascinating gemstones, due their captivating fire and play of colour. The iridescence of precious opal is the result of light diffraction from tiny spheres within the stone. The best opals are found in Australia and cut into cabochons. Another popular opal called fire opal is an intense tangerine orange. Care needs to be taken, not to immerse opals in any chemical or corrosive substance. Opal is the birthstone for October.
Historically known as ‘tears of the gods’ pearls are gems found only in water and are one of the few organic substances used in precious jewellery as they form inside certain species of oyster or mussel. In the late 19th Century a Japanese man called Mikimoto devised a way to culture pearls, these can be of extremely high quality and rarity or fairly inexpensive and freely available. Natural pearls are extremely rare and are no longer found. Pearls, along with moonstone are the birthstone for July.
Freahwater pearls are cultured in freshwater lakes mostly in China and the USA. The larger the pearl is and the better the lustre it has, the longer it will take to grow, and the more expensive it will be. We only use natural colours, including, creamy white, silvery white, grey, pink and lavender. For the most part, freshwater pearls are produced with a much higher turnover than the superior south sea pearls, as the species of mussel used can grow up to 10 pearls at a time, however, some very fine specimens can be found.
South Sea pearl
South Sea pearls are cultured in several different species of oyster, which can only grow one pearl at a time. Taking two or more years to form, they are farmed in the warm waters around Northern Australia, Polynesia and other islands. Naturally white in colour, sometimes with a hint of cream, pink, blue, grey or gold, these pearls generally have a much thicker layer of nacre than freshwater pearls.
Tahitian pearls occur only in one species of oyster, originally found only around Tahiti. However today, they are also farmed around Northern Australia and Polynesia. They occur naturally in all shades of grey, with hints of green, brown, mauve or mink and can sometimes be almost black. It is these natural dark colours that make them unique.
Peridot is a distinctive apple green colour varying in intensity. It is part of the olivene family. It is unusual in that small stones are relatively inexpensive, but larger stones of intense colour and good clarity are of gem quality. Deposits are found in China, Burma, Australia and South Africa. Peridot is the birthstone for August.
Quartz is a crystalline rock composed of silicon dioxide. Semi-precious gemstones belonging to this group include citrine, amethyst, green amethyst, smoky quartz, lemon quartz, lime quartz, rock crystal, rutilated quartz and tourmalinated quartz. The vast range of colours are created by the presence of different minerals. Our quartz gemstones are mostly sourced from Brazil and India.
Rock Crystal, a transparent, colourless quartz, found in Brazil, Madagascar and the USA. The Greek word for rock crystal was krustallos, meaning ice, because it was believed quartz was ice formed by the gods - see quartz. Along with diamonds, rock crystal is the birthstone for April.
Ruby is an intense red with a pink light and in the corundum family. It can very difficult to distinguish between an intensely pink sapphire and a paler red ruby. The finest gemstones come from Burma and other beautiful rubies come from Thailand, Vietnam, Africa, Pakistan and India.
Sapphire is a corundum. All gem quality that is not red in colour is called a sapphire. Most commonly known in shades of blue, sapphire comes in the most spectacular range of colours, from pastel shades of lemon, peach or pink to white to cornflower blues, violets, and intense purples to vibrant greens, yellows and burgundy reds. Sapphires can be found in Madagascar, Sri Lanka and Burma, Thailand, Australia, Brazil, Columbia and most notably Kashmir where the sapphires are prized for their rarity and velvety blue colour. Sapphire is the birthstone for September.
Smoky quartz is sourced in shades of brown from subtle to rich brown to almost black – see quartz.
Spinel is often found in close proximity to corundum and is mined in a wide range of colours from transparent to an intense red, which historically has been confused with ruby. Most prized colours are aubergine, purple-blue, various shades of red and amazing shades of pink to subtler shades of mauve, slate blues and pinks. Found in Burma, Brazil, Madagascar and Australia.
Tanzanite can be found only in Tanzania. It has a distinctive shade of violet blue, from pale to very intense. When mined the crystals are mostly a dull brown colour and are skilfully heated to bring out the vibrant and distinctive colour. Along with turquoise, tanzanite is the birthstone for December.
Tigers eye displays a “cats eye” effect known as chatoyancy. Mostly cut into cabochons or beads, it is brown, black and golden yellow in colour - see agate.
Topaz occurs in a range of different colours from whites, blues, oranges and sherry to natural pinks. It is a gem that can be semi-precious (for example, white topaz) or of gem quality (for example, Imperial topaz) depending on the colour, grade and size. Our topaz is mostly from the USA and Nigeria, also sourced from Brazil, Sri Lanka, Burma, Mexico and Africa.
Tourmaline has perhaps the largest range of colours available including green, blue, turquoise, red, pink, purple, yellow and brown. Most varieties are simply called tourmaline, however, some of very special quality have their own name – pink-red is referred to as rubellite, deep blue tourmaline is called indigolite and a rare turquoise green is known as paraiba. They are found in India, South America, Africa, Russia and many other parts of the world.
Turquoise varies in colour from pale to rich sky blue, to green. The finest blue opaque stone is highly prized, the most coveted shade of blue varies in different parts of the world, for example, in Tibet greener shades are most desired whereas in Iran sky blue is preferred. One of the first gemstones to be mined, it can be found in great abundance in Mexico, the USA, Russia, Chile and Australia. Turquoise, along with tanzanite is the birthstone for December.
Zircon is the oldest gemstone formed at the same time as the world began 4.4 billion years ago. Zircons have beautiful refractive powers. The most popular colours blue, yellow, golden browns, greens and white. Our zircons are often sourced from the Urals in Russia, though they can be found in Norway, Pakistan and the USA.