Rose Cut
A flat-bottomed cut with a domed top of triangular facets. The antique cut that polki descends from.
A rose cut has no pavilion. It is flat underneath with facets rising to a point, usually 3 to 24 of them.
It was designed for candlelight and gives a soft glow rather than sharp fire.
Indian polki is closely related, being an uncut or minimally cut natural diamond set flat over a reflective foil.
When you are buying
Rose cuts look larger per carat than brilliants because all the weight is spread across the face. They suit antique and kundan-style settings far better than a modern brilliant does.
Polki
An uncut, unfaceted natural diamond, set face-up in kundan. Glows softly rather than sparkling.
Kundan
A setting technique where highly refined gold foil is pressed around stones to hold them, with no prongs or claws.
Cabochon
A smooth domed top with a flat base, no facets. The only way to show a cat's eye, star or opal fire.
Diamond
Crystallised carbon, the hardest natural material. Heera in Hindi, and graded on the four Cs.
Cut
How a stone is shaped and faceted. The one thing that most affects how it looks, and the one buyers examine least.