GEMSTONES

 

Natural gemstones are generally minerals, which are beautiful, rare and durable – hard enough to survive constant use or handling without becoming scratched or damage. A few gemstones, like amber and pearl, come from plants or animals, and are known as organic. Their chemistry and structure make them special. Many natural stone can be treated, such as heating, dyeing or bleaching (can improve a stone’s appearance or durability).
Natural gemstones include: emeralds, rubies, sapphires, amber, coral, ivory and pearls.

Others, called synthetic gemstones are identical to natural gemstones in nearly every way, but they are made in the laboratories. They have very similar chemical composition, general physical properties, colours and other characteristics. There are many different methods used in production of synthetic crystals (the common method is the Verneuil process, also called flame fusion). Synthetic gemstones can be usually identified by the differences in their inclusions. They are less expensive, than their natural counterparts.
Common synthetic gemstones are: emerald, sapphire, ruby, opal, amethyst, garnet and spinel, plus synthetic diamond is also being produced.

Imitation gemstones imitate the look or colour of a natural stone, but have completely different physical characteristics. Imitations can be made from anything, often from plastic or glass. A jeweller can easily detect these imitations.
For example an imitation of diamond is cubic zirconia (CZ). A blue piece of glass could be imitation of sapphire.

Some gemstones are more popular then others. Diamond, Sapphire, Ruby, Emerald and Pearl are five major gemstones and they are the most highly prized. All except pearl have a particular cut that brings out their best qualities.

 

Style of cuts

Cabochon cutCabochon-cut

The cabochon cut is the oldest form of cutting gemstone. This simple cut is used to display colours and optical effects of gemstones. The traditional Cabochon is an oval, but can be fashioned into other different shapes (cushion, triangle, rectangle). The Cabochon cut is applied:

 

Brilliant cutBrilliant-cut

The brilliant cut is the most popular cut shape for diamonds and many colourless gemstones. This cut is meant to maximize light returning through the top of the gemstone, making the gem sparkle. The brilliant cut can have several shapes (round, oval, square, pear-shape or heart-shape).
Round brilliant cut shape look like a cone and the standard number of facets is 57+optional culet. This cut was specially developed for diamonds, but today is common for all gemstones.
Oval brilliant cut has an elliptical shape and the standard number of facets is 69. A well oval brilliant cut gemstone can be nearly as bright as a round brilliant cut.

 

Emerald cutEmerald-cut

Emerald cut has large rectangular stepped facets at the top, with slightly cropped corners, making octagonal stone. The sheen tends to display large flashes of these stepped angles on the pavilion of the gemstone (the deeper stone’s pavilion, the richer the perceived colour). The approximate number of facets of an emerald cut gemstone is 50. Emerald cut was developed specifically for emeralds, to protect them during cutting from chipping (today, modern cutting techniques make this less important) and it is used now for a wide variety of gem types. Emerald cut has less sparkle than brilliant cut, but many people like their elegant look and sleek.

 

 

Princess cutPrincess-cut

Princess cut is the second most popular cut for diamonds and lighter coloured transparent gemstones. It is a square brilliant cut gemstone with sharp, uncut corners. Princess cut generally has 76 facets. This cut is effectively a square version of the round brilliant cut, rendering more sparkle and brilliant, because of the extra faceting. The square princess cut diamond is usually less expensive, than round brilliant diamond of the same carat (doesn’t need to be cut off so much diamond weight from a rough diamond). It is relatively new diamond cut.

 

 

Mixed cutMixed-cut

Mixed cut include both step-cut and brilliant-cut techniques. Mixed cut gemstones are usually rounded in outline with the tops cut as brilliants and the pavilions in step cut. This cut is popular for coloured gemstones.