What is a half moon cut diamond?
By Jared James · Last updated 21 May 2026
Definition
A half moon cut is a gemstone cut in the shape of a semicircle, essentially a round or oval stone that has been cut precisely in half along a straight edge. It is used almost exclusively as a side stone flanking a larger centre diamond or coloured stone, and its curved outer edge echoes the shoulder of the ring shank while the straight inner edge sits neatly against the centre stone's setting. The cut works particularly well alongside cushion, oval and round centres, where the curved silhouette of the half moon complements the main stone's shape.
Frequently asked questions
- When would you use a half moon cut as a side stone?
- Half moon stones work best when the centre stone has a rounded or curved silhouette, particularly cushion, oval, round and pear cuts. The half moon's curved outer edge mirrors the centre stone's shape and creates a cohesive, fluid look along the ring.
- How is a half moon cut different from a baguette?
- A baguette is a rectangular step cut with straight sides, giving a sleek, linear look. A half moon is curved on one edge and straight on the other, creating a softer, more flowing effect as a side stone.
- Do half moon cuts hold their value?
- Half moon cuts are specialty shapes used mainly as side stones, so their individual market liquidity is limited compared to round brilliants. Their value in a ring lies primarily in the overall composition rather than as standalone investment stones.
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