Onyx and Mother-of-Pearl Signet Ring in Rose Gold

• Mother-Of-Pearl - Mother-of-pearl, technical name "nacre", is the inner layer of a sea shell. The iridescent colours and strength of this material were widely used in the nineteenth century as an inlay in jewellery, furniture, (especially papier mache furniture) and musical instruments.
  
  In the early 1900s it was used to make pearl buttons. Mother-of-pearl is a soft material that is easily cut or engraved.
  
  Nowadays it is a by-product of the oyster, freshwater pearl mussel and abalone industries.
• Carat - A carat (abbreviated "ct") is a unit of measurement used to describe the weight of a diamond or other gemstone, and separately is a unit of measurement used to describe the weight of precious metals such as gold,.
  
  For gemstones, one carat is equal to 0.2 grams or 200 milligrams. The weight of a diamond is one of the Four Cs (along with cut, colour, and clarity) that are used to determine a diamond's value.
  
  It is important to note that a diamond's weight does not necessarily correspond to its size. A diamond's cut, which affects how well it reflects light, can make a diamond of a lower weight appear larger than a diamond of a higher weight. Additionally, the carat is not the only factor to determine the value of a diamond, other factors such as clarity, colour and cut are important too.
  
  In the gold industry, the purity of gold is measured in carats (abbreviated "ct"), with 24 karats being pure gold and lower carat numbers indicating a lower purity level. So, for example, 18 carat gold is 18/24 or 75% pure gold, and 12 carat gold is 12/24 or 50% pure gold.
• Onyx - Onyx is a form of agate, used from antiquity and popular again in the 1920s and 30s. European onyx is generally green, but can be many other colours, and can contain bands of black and/or white.
  
  This multicoloured stone is widely used for table tops, lamp bases and in jewellery. Some types of onyx are also used for cameos of which the upper white layer is cut away to reveal the colour beneath.

This item has been included into following indexes:

• rings, types - signet 711
• rings, various gems / stones
  • gold not diamonds, other types 5,189
  • onyx 188