Diamond Cut

Never under estimate the cut of a diamond.

Without an " ideal cut" to allow for total internal reflection where light reflects of the diamond facets, then a diamond is dead.

How can it be dead you ask if it was never alive? Well one of the major reasons diamonds are famous is because of their sparkle. Without it, they are just as good as any other gem.
The fire of a diamond is what sets it apart from the rest and it is only achievable if the stone is cut well.

If the diamond is cut too deep, the light escapes from the side facets or pavillion.

If cut too shallow, the light will escape from the bottom of the diamond. Both are very undesirable effects.

Be careful when purchasing your rings that you are not investing in "lifeless" diamonds.

link to Dimamond Rings Info