Emerald and Diamond Ring, 1930s

• 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.
• 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.
• Collet Setting - A collet setting in jewellery is a type of setting that is used to hold a gemstone or other decorative element securely in place. The collet is a ring of metal that surrounds the stone and holds it in place. The collet is typically made of the same metal as the rest of the piece and is often used in vintage or antique jewellery.
  
  In a collet setting, the gemstone is placed into a small metal ring, also known as a collet. The metal ring is then bent or folded over the edges of the gemstone to hold it securely in place. The collet is then attached to the rest of the piece of jewellery, such as a ring or pendant.
  
  One of the benefits of a collet setting is that it allows the maximum amount of light to enter the stone, which can enhance its brilliance and sparkle. It also allows the stone to be seen from the sides, which makes it a popular choice for showcasing particularly beautiful or unique stones.
  
  The collet setting is a classic and elegant setting and it is often found in antique jewellery, particularly from the Victorian and Edwardian periods.
• 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.

This item has been included into following indexes:

• rings, diamond - diamond and emeralds 2,241
• rings, diamond cluster - diamond, cluster with emerald centre 426