When it comes to fine diamond jewelry, four Cs determine quality and price: clarity, carat, color and cut.  Knowing these four factors is essential before making any purchases.  It is important to be informed regarding the 4 C's prior to making this large commitment. 

• Clarity refers to the general quality of the diamond. Notice how diamond graders examine diamonds using light. This allows them to easily spot bubbles, lines, and other imperfections that the diamond may have incurred during its formation. Clear diamonds are more brilliant, and thus, more expensive. Imperfections, sometimes called inclusions, are often invisible to the naked eye.

• Carat is not the size of the diamond, but rather is a unit equal to 200 milligrams. Expectedly, higher carat means greater value. The cost differential as diamonds go up in size is logarithmic, meaning a two carat stone will cost more than twice a one carat diamond.

• In terms of color, colorless diamonds are the most expensive since they reflect the most amount of light. Rainbow colored diamonds are common, but rarely used in engagement rings. Choose the color of the stone to reflect the nature of the occasion.

• The last factor, cut, is often deemed the most important of all Cs. For one thing, cut determines the brilliance of the diamond. The angles and shape a diamond is cut into affects the stone's ability to reflect light. In addition, poorly cut diamonds are also prone to breakage. Some common cuts are marquis, princess and pillow.

Putting all these together, the most expensive diamond jewelry would usually hold a high-carat, clear and colorless diamond. Cut is a highly-subjective factor, although a lot of people prefer a round-shaped diamond for an engagement ring. As one looks for a store to buy diamond jewelry, authenticity and quantity of its collection are not the sole factors to consider. It is also essential that customers find a store that educates and guides them through these four Cs to ensure that they only end up buying fine diamond jewelry.