Buying a diamond: What is the fifth C? There will be approximately 2.5 million weddings in the United States this year and many couples will be searching for the perfect diamond ring. Four factors, known as the "4 Cs," determine the value of a diamond. They are: Cut - The cut is designed to yield the maximum amount of light to reflect back. This reflection, known as brilliance, is an important factor in evaluating the quality of a diamond. A poorly cut diamond will appear dull. Color - Diamonds come in every color of the spectrum, but the most popular gems are white. Stones are graded by color and given designations depending on how far they deviate from the purest white. Colorless stones are graded D and color grading descends through the alphabet, with each letter designating the yellower tint. The best way to see the true color of a diamond is by looking at it against a pure white surface. Clarity - A diamond's clarity is affected by any external irregularities and internal imperfections created by nature when the diamond was formed. Imperfections or "nature's birthmarks" such as spots, bubbles or lines are called inclusions. Although these marks make each stone unique, the fewer the inclusions, the more valuable the stone. Carat - This word for the measurement of a diamond's weight is derived from the carob beans that were used to balance scales at bazaars in ancient times. Because large diamonds are rare, they generally have a greater value per carat. Confidence - Jewelry industry experts add a fifth "C" - confidence in one's professional jeweler. Be sure the jeweler is a member of a professional trade association, such as Jewelers of America (JA). JA requires high ethical standards of its members and provides them with ongoing education. A retailer finder, along with more jewelry information, is available online at www.jewelryinfo.org.