Keeping a diamond's natural shape without misaligning any facets achieves maximum brilliance. Diamonds can be cut incorrectly because they are sold by weight.
A well-porportioned diamond will have more brilliance within its facets that a poorly cut diamond.
A diamond's cut grade is about how well a diamond's facets interact with light, making the diamond more valuable.
Colour
Diamonds are graded by colour scale from D-Z.
A colourless (d) and coloured (z) diamond are both very rare making these diamonds more valuable.
Most diamonds come in the G-H-I-J colour range as they are more affordable but just as beautiful.
Clarity
A diamond is formed as a result of pure carbon that has endured millions of years of intense heat & pressure.
Imperfections are often naturally formed during the process - mother nature's fingerprints.
Naturally flawless diamonds are very rare and treasured.
Imperfections can appear as tiny crystals, clouds or feathers and are rarely visible to the naked eye.
Carat Weight
1 gram = 5 carats and a "point" is 1/100th of a carat (ex 50-point Diamond is half a carat).
A large diamond is rare and valuable, but size does not determine beauty & brilliance.
Two stones of the same carat weight can have different values based on the cut, colour & clarity.