Amethyst

Amethyst is the most striking member of the crystal quartz family. It's usually purple in colour, however crystals have been know to have a colour range of milky white to a very pale lavender. The ancient Greeks believed it to have the power to make the wearer immune to the affects of alcohol. Large deposits of the stone have been found in Brazil and neighbouring Uruguay. Another major source is Madagascar. Other countries known for having deposits of the stone are Canada, Tibet and Sri Lanka. Amethyst has a Mohs hardness rating of 7.

Cubic Zirconia

A stone that is created in laboratories and used as a cheaper alternative to Diamonds. They were first developed back in 1977. When created, the stone is usually optically flawless with no colours. However, colours can be added during the forming process with chemicals. The Mohs hardness rating for CZ is 8.

Karat

Karat (kt / K) is how we measure gold for it's purity. Below is a table showing how pure the gold is at each level.
Karat Percent Gold
24 Kt. 100% Gold
18 Kt. 75% Gold
14 Kt. 58.3% Gold
12 Kt. 50% Gold
10 Kt. 41.7%

Mohs Scale

In the case of minerals and Gemstones, hardness refers first to scratch hardness then to cutting resistance of each mineral. Friedrich Mohs introduced the term 'Scratch Hardness'. The following table shows the scale that he developed which is still in use today.

The Scale

Diamond 10
Ruby, Sapphire 9
Chrysoberyl 8.5
Spinel, Topaz 8
Aquamarine, Emerald 7-8
Zircon 7.5
Tourmaline 7-7.5
Garnet 6.5-7.5
Amethyst, Chalcedony, Quartz, 7
Steel (pocket knife) 7
Jade 6.5-7
Peridot 6.5
Moonstone 6-6.5
Opal 5.5-6.5
Turquoise 5-6
Lapis lazuli 5-5.5
Glass 5
Iron 4
Azurite 3.5-4
Bronze, Coral, Pearl 3
Gold 2-3
Amber, Fingernail, Ivory, Shell, Jet 2.5
Talc 1

Onyx

Onyx comes from the same Greek word which translates to nail or claw. Onyx is a member of the Chalcedony quartz family. Its colour is usually black or white. This stone was very popular with the ancient Greeks and Romans. Onyx has a Mohs hardness rating of 7.

Pearl

There are many types of pearls, including natural pearls, (made with no human interference), Cultured Pearls, pearls made by inserting a small piece of foreign tissue living oyster or Mollusk. Baroque pearls, irregularly- shaped pearls, freshwater pearls, seed pearls and Biwa pearls are pearls that are formed in the freshwater mussel. The Mohs hardness rating for a pearl is 3.

Rhodium

Rhodium is a white precious metal that is quite expensive. Rhodium is often used in the plating of base & precious metals to give it a Platinum-like sheen. The main source of this alloy is South Africa.

Silver

Silver gets its symbol (Ag) from the Greek word Argyros. Silver is a fine, precious metal. Its colour is silver-white and it is often used in jewelry. Silver has to be alloyed (mixed) with other metals in order to use in jewellery production. This mixing of metals makes it more durable and rigid.
Jewellery and Silverware are traditionally made from Sterling Silver (standard silver), an alloy of 92.5% silver with 7.5% copper. Britannia silver is an alternative hallmarked-quality standard of the alloy containing 95.8% silver, often used to make silver tableware and wrought plate. Silver is often plated with Rhodium for a bright, shiny look which does not tarnish as quickly. However, under normal conditions with no plating, Silver will tarnish - it's the mixture of moisture and sulphur in the air we breathe that causes Silver to tarnish.
The largest piece of Silver ever found was in 1440 in Germany. Its dimensions were 2m x 4m with an approximate weight of 20 tonnes. It was named the "Silver Tableö due to its size and shape.
The main area of the world that Silver is mined today is Russia. The country produces around 15% of the world's total output, closely followed by Mexico. Canada, the USA, Peru, Bolivia and Germany have also have notable deposits.

Topaz

Topaz in its purest form has no colour. It is usually coloured by the impurities from the surrounding land. Topaz can be found in many colours, some of which do not occur naturally. Take Mystic Topaz for example. This type of Topaz is created by applying an artificial coat to the stone which gives it that magical look. Blue Topaz in its natural form is very rare, so manufactures heat treat colourless topaz to create a deeper blue - more vibrant than a natural stone will ever posses. Topaz can be found in many countries around the Globe including Germany, Japan, Norway, the USA, Sri Lanka, Afghanistan and the Czech Republic. Topaz has a Mohs hardness rating of 8.

Vermeil

Vermeil is a French word that was introduced in to the English language in the 19th Century. Vermeil is a process where Sterling Silver is plated with Gold (at least 10K) and the layer has to be 1.5 micrometers thick to be considered true Vermeil.