Diamond Buying Advice

2 Carat Diamond Shapes Emerald Cut Diamond and Princess Cut Diamond
Mark Johnson / Getty Images

Buying a diamond can be an important (and expensive) event, but it can be confusing.

  • Should you go for a larger diamond or choose a smaller stone of higher quality?
  • Is color an important consideration?
  • How does the cut affect the stone?
  • Is a solitaire diamond best, or is a cluster of stones a better choice?

Gem and jewelry expert Antoinette Matlins offers advice to help you buy a beautiful quality diamond without blowing your budget. She helps you juggle the elements of a diamond ring and its setting to create the perfect engagement ensemble. Read her interview for important diamond buying advice and insight. 

The Interview

Question: How should an inexperienced person shop for a diamond engagement ring?

Ms. Matlins: Before you buy a diamond engagement ring, take the time to understand the quality factors known as the 4Cs--color, clarity, cut, carat—so you feel comfortable juggling them to get just the right combination for you. Knowing how to juggle the 4Cs can enable you to achieve a high-budget look at a reasonable price.

Shop around to educate your eye, to learn what appeals to you, and to familiarize yourself with current styles.

Question: Which of the 4Cs do you think is the most important?

Ms. Matlins: Cut is the most important factor affecting a diamond's beauty and cost, and can also affect its durability.

Sparkle and brilliance are determined by the cutting because it is the cutting that affects the way light travels through the stone, how much is reflected back to the eye, and how much "leaks" out the back.

  • A stone that is cut too thin will have a lot of light leakage so it won't sparkle much and will look lifeless.
  • A well-cut diamond will have lots of sparkle, lots of liveliness.
  • A poorly cut diamond should sell for half the cost of an exceptionally cut diamond.
  • Some cutting faults can make a diamond prone to breaking.

Don't let anyone convince you that a high clarity grade is necessary to have a brilliant, sparkling diamond, or that cut refers to the shape. You'll make a big mistake unless you understand what these two widely misunderstood Cs are all about.

Question: Do you believe diamond clarity is just as important?

Ms. Matlins: Clarity is often mistakenly believed to be the factor that affects the amount of sparkle and brilliance. This is not true. Clarity refers to the presence of microscopic features that formed within the diamond as it crystallized. If readily visible without magnification, poor clarity will greatly reduce the value, but otherwise, clarity has minimal impact on beauty or desirability.

Question: When it comes to a diamond's carat weight, is bigger always better? Are there ways to make a diamond look larger than it is?

Ms. Matlins: There are 100 points to a carat, but the cost of a diamond increases significantly when it reaches the full carat mark, and for each carat thereafter. So try to find a diamond that weighs 90-points (9/10ths carat), for example, rather than a full 1-carat, or 1.90 carats rather than a full 2-carats, and so on. When set, no one can see the difference, but you'll enjoy big savings in cost.

If the size is important to you, consider shapes other than round. While the round, brilliant-cut diamond is considered by most to be the cut that exhibits the most brilliance, it normally looks smaller than diamonds cut in other shapes. Consider an oval, pear-shaped or marquise, all of which will look larger than the round.

Consider a design that uses several stones rather than one large diamond. A fine diamond weighing one carat, set in a classic Tiffany-style setting, might cost $7,500 while the cost of a ring containing three stones with a total weight of one-carat, only $3,250; or a diamond band containing nine diamonds with a total weight of one-carat could be less than $2,000.

Using wider, innovative designs can create a very impressive look for a diamond under 1-carat, especially if your fiancée's fingers are very large or unusually long and you are concerned that a smaller diamond will look out of balance on her hand.

Question: Diamonds in the top color grades are much more expensive than lower grades. How about some tips to help us evaluate diamond color?

Ms. Matlins: If you think you can't afford a colorless diamond (D-F), don't fret. Within the top 10 color grades, most diamonds still look very beautiful when mounted. Setting the stone in white gold or platinum can make it appear whiter. Or, if the stone has a noticeable yellowish tint, try setting it in yellow gold—the diamond will look whiter and the tint will be much less noticeable.

Question: Do you have any final diamond advice for us?

Ms. Matlins: A diamond does not have to be Flawless to be beautiful and precious. Don't ignore diamonds in the slightly included (SI) range. In a brilliant-cut diamond--round, oval, pear-shape, marquise, heart-shape--no one can see any difference between a stone that is graded flawless and one graded SI, even though the SI is seven grades lower. There is absolutely no visible difference. It is much less rare but no less beautiful.

You won't see the flaws in a well-cut stone, but you will see big savings! And as a symbol, what could be more appropriate for marriage...being able to see and appreciate the beauty within, despite a few, unimportant imperfections.

About Antoinette Matlins

Antoinette L. Matlins, P.G., is an internationally respected gem and jewelry expert, author, and lecturer. Her books are widely used throughout the world by consumers and professionals in the gem and jewelry field alike.

Editor of National Jeweler magazine for almost a decade, her articles on buying and selling gems, jewelry, and gem investment have appeared in many national and international consumer and trade publications.

Trained by her father and co-author, Antonio Bonanno, she has gained wide recognition as a dedicated consumer advocate. Ms. Matlins has spearheaded the Accredited Gemologists Association's nationwide campaign against gemstone investment telemarketing scams. She has been seen on ABC, CBS, NBC, and CNN, educating consumers about gems and jewelry and exposing fraud.

Edited by: Lauren Thomann