Anis clay, silt or gravel that was carried by a rushing stream and deposited in locations where the stream slowed down.
Ais a measure of weight used when referring to gemstones. This is very different to the karat term used when referring to the purity of gold. A is defined as 200 milligrams. That means there are 5 carats to the gram. Each can be further divided into 100 points. This allows for small stones, generally those below 1 , being measured in points, rather than fractions of a .
Theare a number of gemstones that were traditionally considered the most precious, above all others. This term is not generally used anymore. It started in antiquity and was based largely on religious use, and the perceived rarity of the stones at the time. Amethyst, one of the original , was considered rare and thus highly valued, until large deposits were discovered in a number of areas.
gemstones are cut by professionals with the primary aim of achieving the best quality finished stone. These stones will demand higher prices, but there is usually no comparison between a gemstone and a gemstone. With stones the should meet, polishes should be perfect and the stone should be brilliant. If you are looking for an investment stone, it should be and should be amazing to see.
is considered to be the ideal grade of Amethyst. It has a purple hue of about 75-80 % and blue and red tones of about 15-20%.
referes to the ability of some materials to split visible light into defined beams of different colours (wavelengths). material usually splits into two colours, though the term is used often even when the material produces several distinct colours.
refers to the bending of light that occurs when a light wave encounters an obstacle or a slit. The light bends around the corners of an obstacle or aperture.
Gemstoneare usually flat surfaces cut into the gemstone in a uniform and planned pattern. They generally cover all surfaces of a gemstone. In modern times gemstones can have curved surfaces, either concave or convex. The must be positioned accurately, according to specific angles, to best reflect the light back to the viewer, creating that wonderful brilliance we all love. The angles depend on the type of gemstone, each type of gemstone having a different refractive index.
The crown of a gemstone is that part above the girdle. This is the top of the gemstone and thus the face you would normally view after the stone has been set in jewellery.
Theis the point at the bottom of the gemstone. To prevent chipping, in some gemstones the culet has a flat surface rather than a point.
The girdle of a gemstone is the widest part of the gemstone. It separates the crown from the pavilion. Looking from the top of the stone it defines its outline. Looking from the side the girdle is usually quite thin, though it needs to be thick enough so a jeweller can set the stone without breaking the girdle. A very thick girdle can be a good indication of a bad gemstone cut. To increase the weight of a stone some cutters cut a deep girdle. This can make the stone darker and harder to set, besides ruining the look of the stone generally.
Theis found on certain gemstone cuts, instead of a culet. Cuts such as the emerald cut and the oval cut can't have a point and instead have an edge called a keel.
The pavilion of a gemstone is the bottom of the faceted stone. The area below the girdle.
is the process used to expose an object to radiation, either by nature or artificially. If applied artificially it is done so to achieve a specific purpose, such as improving the colour of a gemstone. In the case of gemstones, the process mimics the process that can take place naturally, though over a much longer period.
Ais a small magnifying glass used by jewellers and watchmakers.
In mineralogy,is the way light interacts with the surface of the mineral. Many terms are used to describe . Terms such as adamantine, greasy, dull, vitreous and more. A common term is vitreous, which refers to a glassy .
Ais the point where three (3) or more meet.
Thein Europe (or medieval period) was a period that spanned the 5th to the 15th century. It started with the fall of the Western Roman Empire and continued through to the Renaissance. It is so named because it is the middle period of three traditional divisions of European and Western history. The three periods being Classical Antiquity, the Medieval Period and the Modern Period.
of Mineral Hardness
Theof hardness in minerals was created in 1812 by the German geologist and mineralogist Friedrich Mohs. It is a scale that characterises scratch resistance of minerals to other harder minerals.For example, how Sapphire is scratched by Diamond. While Mohs created this scale, the concept of observing how one mineral scratches another dates back to antiquity, being mentioned in the On Stones treatise by Theophrastus, c. 300BC.
, the coating that appears on the inside of some mollusc shells, is an organic-inorganic compound. is also the natural coating applied to pearls by molluscs. It's a very resilient and strong surface that has beautiful iridescent appearance.
are used by the followers of various religions to count the repetitions of things like chants, devotions and prayers. These include the Bahá'í Faith, Buddhism, Christianity, Hinduism, Islam and Sikhism
Most gemstones in affordable jewellery today are generally produced in bulk, using a mass production cutting method. This may be by machines or low cost labour. This means thatmay not meet, polishes may not be complete, brilliance may be less than desirable and so on. stones are cut for weight, because they are priced per , and not brilliance. This means that the correct angles may not have been used. You can see this in stones where the pavilion has been bellied out to give more weight. The table may also be higher than desirable. The alternative to a stone is stone that has been cut to achieve the best looking stone, even at the cost of reducing the weight. However, stones demand a higher price per and thus the loss in weight is offset by the quality of the final stone.
is the change in direction of a light wave at an interface between two different media, so that the light is returns back into the medium from which it originated.Your bathroom mirror being the perfect example.
is the change in direction when a light wave passes from one medium into another. A common example can be seen when placing a stick into water and it appears to bend. In fact, the light from the stick is changing direction as it exits the water and enters the air.
is a much lighter shade of purple Amethyst, more lavender or lilac. It has become very desirable in recent times.
Ais an object, typically an inscribed ring or stone, that is thought to have magic powers and to bring good luck.
According to the Book of Exodus, this is Theworn by the High Priest of the Israelites. Sometimes called the Breastplate of Judgement. The breastplate contained four rows of three stones. One stone for each of Jacobs (Israels) twelve sons, set in their order of birth. Because Hebrew is a right to left script, the stones were probably ordered the same way on the breastplate.
Theof a material is a measure of its ability to conduct heat.
Ais simply a chemical element that is present in an object, such as a gemstone, in a very low concentration (a trace amount). In gemstones, can alter the gemstone remarkably, such as changing its colour.