Heart Cut
A brilliant cut in a heart outline. Difficult to cut well and unforgiving of asymmetry.
A heart is essentially a pear with a cleft cut into the rounded end.
Symmetry is everything: the two lobes must match and the cleft must be distinct and centred.
Below about half a carat the outline stops reading as a heart at normal viewing distance.
When you are buying
Avoid small heart-cut stones. The shape needs size to be legible, and a poorly defined heart just looks like a misshapen pear.
Pear Cut
A teardrop outline, round at one end and pointed at the other. The classic pendant and drop-earring shape.
Round Brilliant
The standard round cut with 57 or 58 facets, engineered to return the maximum light. The most common cut there is.
Cut
How a stone is shaped and faceted. The one thing that most affects how it looks, and the one buyers examine least.