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History & Introduction


Agate comes from the quartz (silicon dioxide) family. Quartz mineral after feldspar is the mineral available in plenty on the earth’s crust.

Agate was probably discovered around the 3rd or 4th century (BC) by a Greek philosopher, Theophrastus, he named after the river 'Achates', where it was found. The Achates River, which flows from Sicily, Italy, which is called Dirillo River now. Agate gemstone is considered in the possession of man since ages. Jewellery during the Stone Age, along with spear and arrow tips, is found in prehistorically grave sights. In 3500 B.C agate were found in Egypt, even the early inhabitants of Mesopotamia, the Sumerian styled the agate gemstone into various items like signet rings, cylinder seals, beads, and other ornamental objects created with this versatile stone. The agate gemstone was first discern by the Sumerians from common minerals and they are the first to give specific gems extraordinary attributes. It was believed that the agate gave special favour with the gods to the wearer. However, the origin of Mesopotamia’s agate stone was never determined even though the stone was used in plenty.

Microcrystalline aggregates the modern name used is linked to the western literature. The Greek writer Theophrastus (372-287 B.C.) mentioned it as beautiful stones. It is available in huge masses and in varieties of colours, hence it has different names: cerachates [chalcedony], leucachates [chalcedony], iaspisachates [agate-jasper], smaragdachates [green agate], haemachates [red agate or agate with red] and dendrachates [moss agate].

There are certain colours in found in agate that purely capable of curing the sting of deadly spiders and scorpions. As Orpheus writes that if anyone wears a piece of the Tree-Agate upon their hand, the immortal Gods will be happy. It is explained in Roman tradition that if a wrestler wears a specific colour of agate gemstone than he is invincible. Pliny's writings gives methods to test a stone to be certain as well as to see that the colour is true. Powdered agate originates from India and is a green stone. Agate from Egypt or Crete, red in colour, is best when a cure for spider or scorpion bites is required.

Since various ancient cultures the virtues of the Middle Eastern Lore is passed to us. The various colours of Agate gemstone is taken with distinct and separate virtues by the Egyptians.

Recognise - Fibrous and granular are the varieties formed when cryptocrystalline quartz are broken. Chalcedony is the fibrous variety of quartz. Agate gemstone is the banded type of chalcedony quartz, the specimen which is lighter and solid-colour is called as simple ‘chalcedony’. Usually the consumers get confuse when they go to shop agate gemstone and instead find the different kinds of it. The reason is that the stones are in general referred to using peculiar trade names, such as ‘banded agate’, ‘carnelian’ and ‘sardonx’, while simultaneously traded as just chalcedony, chalcedony quartz also the plain quartz.

Availability - Agate was probably discovered around the 3rd or 4th century (BC) by a Greek philosopher, Theophrastus. He named the stone after the river ‘Achates’ (Greek: Aχάτης), where it was found. The Achates River is situated in Sicily, Italy, which is called Dirillo River now. Agate deposits are available almost all over the world like Argentina, Uruguay, Australia, Myanmar, Brazil, Mexico, Botswana, India, and the USA. Agate is usually originated alongside many other types of rock, however it is primarily categorized as volcanic rock.

Usages - Cameos and ornamental objects are carved from Agate, and also to famous polished slabs. It is even used in inexpensive gemstone jewellery, mainly as beads in necklaces, earrings, bracelets and cameos. Agate is also created to beautiful and ornate bookends and carved figures.

Buying Guide

Colour - The colours that are available in Agate gemstone are many and in different patterns. Though, there seems to be colours that are in general as others, almost all agate will be colourful because of unique banding. Single-colour agates are found in original form on the earth’s crust, to get unicolor these days, the stone is dyed. Agate with one colour are traded with names like sard and carnelian. The colours of agate stone are red, black, white, green, blue, yellow, orange, pink, brown, purple and grey. Agates found in South America don’t have any special markings. They even occur naturally in a dull grey colour. Agates gemstone from the once plentiful mines of Idar-Oberstein in Germany that at present are depleted and popular for their vibrant and strong colours, particularly the natural pink, brown and red.

Clarity and Lustre - Naturally, cryptocrystalline quartz gets discern from microcrystalline quartz by lustre and clarity; the cryptocrystalline clarity ranges typically from translucent to opaque and lustre frequently maximum shows waxy or dull like agate and chrysocolla. On the other hand, microcrystalline quartz is even naturally shows transparent to translucent and with vitreous lustre like citrine, amethyst and rose quartz.

Cut and Shape - Agates is also available in great sizes and with various shapes. Number of agates are cut into en cabochon to add on their beauty, however they are even available in free-form slabs and plain cuts. Not only this the stone in general is used for ornamental designs such as cameos and other carvings.

Treatment - Agate is not treated naturally, however it is dyed easily to develop the colour since it is quite porous. The price of agates are reasonable whether they are dyed or not. In fact the sellers always disclose whatever treatments are given to their knowledge. It is not easy to test agate for dyeing without breaking the stone. Absence of proper equipment is found in most gem labs. Agate is the common choice for beading and tumbled jewellery. Maximum tumbled and agate beads are dyed to enhance colour. Bright unicolor agates, especially especially from Brazil, are dyed naturally though untreated specimens are present.

Gemmological Characteristics:

Chemical Formula SiO2 - Silicon dioxide
Crystal Structure Cryptocrystalline - microcrystalline aggregate (trigonal)
Colour multicolour and banded
Hardness 6.5 – 7
Refractive Index 1.530 - 1.540
Density 2.60 - 2.64
Cleavage Not found
Transparency From translucent to opaque
Double Refraction / Birefringence Till 0.004
Lustre Waxy to dull
Fluorescence It varies according to the bands of green, yellow, blue-white; slightly strong
Streak White
Fracture Conchoidal
Tenacity Brittle
Other ID Marks 1) In general fluorescent is mainly in green or white. It even display fluorescent banding patterns where some of the bands will fluoresce more strongly.
2) Triboluminescent
3) Piezoelectric
Complex Tests In hydrofluoric acid
In Group Silicates; Silica Group; Tectosilicates;
Striking Features Banding patterns
Environment Agate is available in all mineral environments, however it is prevalent in igneous rocks like the basalt.
Rock Type Sedimentary, Igneous, Metamorphic
Popularity (1-4) 1
Prevalence (1-3) 1
Demand (1-3) 1

Classification:

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