Read about Gemstones and their properties

From Wikipedia

Many precious and semiprecious stones are used for jewellery. Among them are:

Amber

Amber, an ancient organic gemstone, is composed of tree resin that has hardened over time. The stone must be at least one million years old to be classified as amber, and some amber can be up to 120 million years old.

Amethyst

Amethyst has historically been the most prized gemstone in the quartz family. It is treasured for its purple hue, which can range in tone from light to dark.

Emerald

Emeralds are one of the three main precious gemstones (along with rubies and sapphires) and are known for their fine green to bluish green colour. They have been treasured throughout history, and some historians report that the Egyptians mined emerald as early as 3500 BC.

Jade

Jade is most commonly associated with the colour green, but can come in a number of other colours as well. Jade is closely linked to Asian culture, history, and tradition, and is sometimes referred to as the stone of heaven.

Jasper

Jasper is a gemstone of the chalcedony family that comes in a variety of colours. Often, jasper will feature unique and interesting patterns within the coloured stone. Picture jasper is a type of jasper known for the colours (often beiges and browns) and swirls in the stone’s pattern.

Quartz

Quartz refers to a family of crystalline gemstones of various colours and sizes. Among the well-known types of quartz are rose quartz (which has a delicate pink colour), and smoky quartz (which comes in a variety of shades of translucent brown). A number of other gemstones, like Amethyst and Citrine, are also part of the quartz family. Rutilated quartz is a popular type of quartz containing needle-like inclusions.

Ruby

Rubies are known for their intense red colour, and are among the most highly valued precious gemstones. Rubies have been treasured for millennia. In Sanskrit, the word for ruby is ratnaraj, meaning king of precious stones.

Sapphire

The most popular form of sapphire is blue sapphire, which is known for its medium to deep blue colour and strong saturation. Fancy coloured sapphires in various colours are also available. In the United States, blue sapphire tends to be the most popular and most affordable of the three major precious gemstones (emerald, ruby and sapphire).

Turquoise

Turquoise is found in only a few places on earth, and the world’s largest turquoise producing region is the southwest United States. Turquoise is prized for its attractive colour, most often an intense medium blue or a greenish blue, and its ancient heritage. Turquoise is used in a great variety of jewellery styles. It is perhaps most closely associated with southwest and Native American jewellery, but it is also used in many sleek, modern styles. Some turquoise contains a matrix of dark brown markings, which provides an interesting contrast to the gemstone’s bright blue colour.

Some gemstones (like pearls, coral, and amber) are classified as organic, meaning that they are produced by living organisms. Others are inorganic, meaning that they are generally composed of and arise from minerals.[12]

Some gems, for example, amethyst, have become less valued as methods of extracting and importing them have progressed. Some man-made gems can serve in place of natural gems, an example is the cubic zirconia, used in place of the diamond.