Before you shop, you need to get a good education about diamonds and what makes one more valuable and beautiful than the next. Become familiar with our original diamond tutorial with basic and advanced information about the 4 Cs (cut, color, clarity and carat weight) as well as a video to watch.
 
You can get answers to all of your questions on our Diamond Q&A forum.

You can not learn, or in many cases even see, the differences in a set diamond. Once a diamond is set, the prongs, or bezel, not only cover part of the diamond (thereby possibly hiding flaws), but they also make exact color determination almost impossible (diamonds often draw color from the surrounding metal).

Ask a dealer to explain to you the differences in diamonds. Let him/her show you the differences comparing one loose diamond to another. Be sure you see all the different cuts (including proportions), colors, clarities and carat-weights and try to see them in a number of different types of lighting.

Always look at your diamond through a jeweler's loupe or a microscope, which will reveal imperfections not seen with the naked eye.

Ask for the table percentage. This determines how well cut the stone is with a good table percentage being between 53-60%. Is the girdle faceted; is the culet open or closed; is this a new stone; has the stone been enhanced in any way. Always have the diamonds flaws plotted on a drawing of the stone. That way you will be able to identify your diamond by the location of its blemishes and inclusions.

Ask whether the stones have certificates. Certificates from GIA and AGS are the most recognized. Ask whether an appraisal from an accredited appraiser is included in the price. A certificate gives the scientific data of the stone; an appraisal gives the financial value of the stone. Your insurance company will require it.

In other words, don't buy a High Color/Low Clarity or Ideal Cut/Low Color Diamond. You pay a serious premium for getting say an E Color Diamond. What's the purpose of paying that premium and then buying an SI2 Diamond? Why not go down a color or two and increase one or two clarities? This is a very common practice.

Decide which of the 4Cs your care most about. Be sure you see it all. Decide if color is the main critical factor to you, or clarity, or cut, or size. You will learn fast that as the four C's change so does the price (or at least it should).

The best way to know prices for the specific Diamond you are looking for is to shop around for a Certified Diamond of a quality range you desire. Compare only "apple to apple", same quality of diamonds with each other.

Do not hesitate to ask for how long has this diamond company been in business and what credentials it has.

Most retailers dramatically increase prices. Never pay the sticker price unless you are sure they are already giving you the fair price.

Always insist that the final sale be contingent upon the opinion of an independent accredited appraiser.