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How may the size of the culet influence your diamond purchase?

How may the size of the culet influence your diamond purchase?

Here we shall delve into a part called the culet, this tiny little part at the tip of a diamond which may even seem irrelevant to some but can play an important role for several reasons.

  • 0.50 carat solitaire ring (half set) in yellow gold with side diamonds From USD 3.060
    (excl. VAT)
  • 1.00 carat solitaire diamond ring in white gold From USD 1.710
    (excl. VAT)
  • 1.00 carat classic diamond earrings in white gold with six prongs From USD 670
    (excl. VAT)
  • 0.50 carat solitaire ring in white gold with princess diamond and side diamonds From USD 2.110
    (excl. VAT)

The Culet

A round brilliant diamond is composed of either 57 or 58 facets. What makes this difference? Whether an extra tiny polished facet at the tip of the diamond and parallel to the table, called culet, has been cut or not. This applies mainly to round brilliant diamonds and not as much to most fancy shaped diamonds or old cuts.

The main purpose of a culet is actually to prevent damage to the point of the diamond. When there is no culet it is more likely for a diamond over time to get a little chip at the tip. It is not a mandatory feature to look for when buying a diamond but depending on the size of the diamond and the setting you intend to use it can be considered.

Should you wish to set your diamond high on a ring and with a ring structure that protects the stone all around, then of course you can buy a diamond that has no culet.

What happens when the culet is too large?

The size of the culet is determined in percentage which can be calculated by dividing the cult size in millimetres by the average diameter of the stone and multiply the result by 100.

Based on this result, the culet will be defined as very small and small when measuring about 1.5%, to very large and extremely large when measuring up to 15%.

None, very small and small are the sizes that are best evaluated visually. Medium could be tolerated depending also not the size of the diamond, but beyond that it wouldn’t be recommended.

If the size of the culet is too large, there is what we call a “window”, which literally allows you to look through the diamond. Should you have doubts, try this little trick, you hold your diamond with the tweezers face up and move a pen underneath the diamond, if the culet facet is too big, you will literally be able to see the pen across the diamond.

When a diamond is already set into a ring, we do know it is not as easy to see, but once you know what to look for, you will be able to spot it even in set rings.

Should this particular part of the anatomy of a diamond be considered when buying a diamond? We believe so, as the price can vary depending on the size of the culet.

If you are considering buying a diamond and would like some guidance on this particular subject, the team at BAUNAT would be very happy to assist you further with your query.


The diamonds as well at the jewellery at BAUNAT are certified by the most reputed labs and we know we can provide you with what you are looking for. 

Written by: CHLOÉ POUPON-DUMONTET Diamond Jewellery Advisor

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