Kutchinsky Onyx and Diamond Ring

• Circa - A Latin term meaning 'about', often used in the antique trade to give an approximate date for the piece, usually considered to be five years on either side of the circa year. Thus, circa 1900 means the piece was made about 1900, probably between 1895 and 1905. The expression is sometimes abbreviated to c.1900.
• 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.
• Pave Setting - Pave setting is a style of setting stones in jewellery where the small stones are placed close together in holes drilled in the metal, the burr of the metal around the stone being pressed over the edges to hold the stone in position.
• Brilliant Cut - In their naturally occuring state diamonds have little life or sparkle and for many centuries were simply cut in half and worn in amulets. Invented at the end of the 17th century by a Venetian diamond cutter, a "brilliant cut" diamond has 58 facets arranged in a regular geometric relationship, with 33 above the crown and 25 below on the pavilion.
  
  The introduction of the brilliant cut increased the popularity of diamonds in jewellery as it was the first cut to reveal the fire of the diamond, with the light being internally reflected from one facet to another, and was superior to the previously used table cut and rose cut.Variants to the brilliant cut have emerged since the end of the 17th century, but the popularity of the original brilliant cut has continued to the present time, where it is still the most commonly found cut.
  
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• 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:

• Kutchinsky (London) - jewellery 12
• rings, diamond
  • diamond and onyx 198
  • diamond rings, pave set 381
  • diamond, multiple diamonds 4,985
• rings, diamond solitaire - diamond solitaire / claw set brilliant cut 6,808