Van Cleef & Arpels Winking Cat Brooch

• 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.
• 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.
• 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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• Assay / Assayed - Assaying is the testing of a metal, most commonly silver and gold to determine its ingredients and quality. In Britain, once an item of silver or gold has been assayed, a mark is stamped on it, certifying its purity. Known as hallmark, it derives its name from the Guild Hall of the Goldsmiths' Company, who recieved its Charter in 1327 giving it the power to assay and mark articles of gold and silver.
• Emeralds - Emeralds have been used in jewellery making for thousands of years, and are prized for their deep green colour, which is caused by the presence of chromium and vanadium in the mineral beryl. Because of their rare colour, emeralds are often more valuable than diamonds of a similar size and quality. In jewellery making, emeralds are typically cut into round or oval shapes to maximize their color and clarity. They are often set in gold or platinum and used as the centrepiece of a piece of jewellery, such as a ring or necklace. They can also be used in combination with other gems, such as diamonds, to create intricate and beautiful designs.
• Cabochon Cut in Jewellery - A cabochon cut is a type of gemstone cutting where the stone is cut and polished in a convex shape with a flat bottom and a domed top, with no facets. This type of cut is typically used for opaque or translucent stones that have natural patterns or inclusions that are best displayed in this type of cut. Examples of stones that are often cut as cabochons include turquoise, opal, and moonstone.

This item has been included into following indexes:

• brooches, depicting - cat, chat 44
• brooches, diamond
  • diamond and emeralds 209
  • diamond and onyx 44
  • diamond and ruby 435
• brooches, set with
  • diamonds 511
  • rubies not gold 99
• Van Cleef & Arpels (France) - brooches, designers 36