You will probably have heard of diamond sizes being referred to in carats. It is a diamonds weight that is measured in carats. CT is short hand for carat, for example half a carat will often be written as 0.5ct.
Photographed below, are diamond sizes that I often work with. They are shown on my hand for scale and have their ct weight and the diameter in mm labelled.
Engagement rings
Diamond size is one of the considerations to be made when choosing an engagement ring. Popular engagement ring diamond sizes are between 0.25ct and 0.5ct.
Trilogy engagement rings
Trilogy engagement rings have three stones, typically one larger centre stone flanked by smaller stones. The three stones can represent the past present and future, with the centre stone signifying the present.
The size of this central diamond is 4mm, and the flaking diamonds are 2mm in size.
White gold set engagement rings
The setting (the metal around the diamond) can look great in white gold even if the band of the ring is yellow gold. The white gold setting frames the diamond making is appear brighter and can give the impression of a larger diamond. This diamond is 4mm or 2.5ct.
Rose cut diamond engagement rings
The cut of a diamond refers to the shape of the stone and the arrangement of the facets on the surface of the stone. The most popular shape of diamond is "round brilliant cut" (as featured in the rings above). A more unusual cut of round diamond is "rose cut". Rose cut diamonds have lots of character, however do reflect the light less than the more typical "brilliant cut".