How to Shop for a Diamond Ring

This publicity photo provided by Gemological Institute of America shows seven diamond cut shapes, from left to right: cushion, Asscher, emerald, modified radiant, oval, marquise, and pear. A simple round cut is the most common for modern diamond rings but some of the more unusual shapes, which have a retro look, are experiencing a resurgence, according to Melissa Colgan, senior style editor for Martha Stewart Weddings, because they are being seen on celebrities. (AP Photo/Gemological Institute of America)

This publicity photo provided by Gemological Institute of America shows seven diamond cut shapes, from left to right: cushion, Asscher, emerald, modified radiant, oval, marquise, and pear. A simple round cut is the most common for modern diamond rings but some of the more unusual shapes, which have a retro look, are experiencing a resurgence, according to Melissa Colgan, senior style editor for Martha Stewart Weddings, because they are being seen on celebrities. (AP Photo/Gemological Institute of America)

New York — Buying a diamond ring can be intimidating. What do you look for? How much should you pay? Should you buy online or in a store?

Demystify the process by learning about the four C’s: carat, color, clarity and cut. This system of grading diamonds was developed 60 years ago by the Gemological Institute of America.

Then do some research online or visit jewelers. You’ll soon understand your options.

Here’s a primer on the four C’s and other advice.

The Four C’s

∎  Carat is a weight measurement. A 1-carat diamond weighs 200 milligrams. But there’s no ideal size for a diamond. It depends on your budget and taste. Some women want a big rock; others prefer a delicate, less blingy look.

Small diamonds are cheaper than large diamonds. A ring with three small diamonds totaling 1 carat costs less than a single 1-carat stone of similar quality.

∎ Color is graded by letter, starting with D for rare, colorless diamonds. E and F are considered excellent, but G or H diamonds will look just as good to the naked eye.

Farther down the scale, you’ll notice differences. “If you put a K color beside a G color, you’ll notice more yellow in the K,” said Russell Shor, senior industry analyst for the Gemological Institute.

∎ Clarity measures diamond flaws, called inclusions, which might appear as tiny spots, clouds or cavities in the stone. The clarity grade SI stands for “slightly included.” VS is a better grade, “very slightly included.” VVS is even higher, “very, very slightly included.” Most inclusions in the VVS-SI range cannot be seen by the untrained eye “unless someone tells you where it is,” Shor said.

∎ Cut measures workmanship, rather than a diamond’s inherent qualities. The way a stone is cut enhances sparkle and luminosity and can hide flaws. The best cut rating, ideal, is rare. About a third of diamonds are rated fair, good or very good.

The Formula

What should you look for in each of the C’s?

“The one thing you should not trade off on is the quality of the cut,” said Shor. “Even a nice color stone, if not well-cut, will be dull and lifeless. But if it’s a middle color — like K — and it’s got a real excellent cut, it will pop and flash with all the sparkle that diamonds are famous for.”

After choosing the cut, “balance the color, clarity and carat weight based on your personal preference to find the best diamond for you and your budget,” said Amanda Gizzi, spokeswoman for Jewelers of America.

For example, for $2,000, you might pick a 1-carat, K-color stone with a slight inclusion, or a half-carat, G-color, with a very slight inclusion. An L or M-colored diamond at that price “will get you a 2-carat honker, but you’ll definitely notice the yellow and you’ll see some inclusions,” said Shor.

Consumers pay $3,500 on average for engagement rings, according to Jewelers of America.

On the low end, Shor recommends spending at least $700 to $1,000 to get “something that’s not too small and of reasonable quality, a respectable half-carat stone.”

It’s easy to compare options online. At BlueNile.com, set your price range, then play with carat size and the other C’s to see tradeoffs.

Shape and Style

Engagement rings traditionally feature gold bands with a center diamond, though some have smaller diamonds on either side. Melissa Colgan, senior style editor for Martha Stewart Weddings, says the engagement ring that Prince William gave to Kate Middleton, a large sapphire surrounded by diamonds, has increased interest in rings with other gemstones.

Diamonds can be cut into many shapes. Round, the most common, offers “the biggest bang for your buck because the difference between the raw and cut diamond is smaller,” Colgan said.

But she said unusual shapes with retro looks and names like marquise, Asscher and pear are having a resurgence, partly because celebrities are wearing them.

Whether a shape is flattering depends on your fingers. “If you have long thin fingers, you can wear something like Asscher or princess that is more square-cut,” Colgan said. “If you have shorter fingers or muscular hands, marquise or oval will elongate your fingers.”

But long nails don’t mix with oval: “It looks like you’ve got a weird nail in the middle of your hand.”

Online or Brick-and-Mortar?

Many major brands, including Macy’s, Kay, Zales, Tiffany and even Costco, sell diamonds both online and in stores.

Some retailers sell online only. Gemvara.com’s site is fun for customizing designs. Just click to see how a ring looks with diamonds and sapphires, versus diamonds and rubies, or with white versus yellow gold.

Blue Nile has sold engagement rings to 325,000 couples over the Internet, including one for $1.5 million.

Nervous about ring size? Blue Nile will mail a free plastic ring-sizer with no obligation to buy. Many retail stores offer 30-day returns with no penalty as well. That’s important for surprise proposals in case the bride-to-be says no, or if she says yes but wants a different ring.

These days, though, couples often shop together for a ring.

“It’s perfectly OK to say, ‘Let’s just go and look at things together,’ ” said Colgan, of Martha Stewart Weddings. “This way she knows what he can afford and he knows aesthetically what she wants.”

Some customers prefer online shopping so they won’t be pressured by an aggressive salesperson. But most diamond rings are bought in person, according to Jewelers of America, citing the 2011 Wedding Report, which found that only 11 percent of engagement rings are bought online. Most people want to see, touch and try before buying.

A new online retailer called Ocappi.com offers to bridge the gap between in-person and online shopping by mailing out “try on rings” made from silver and cubic zirconia.

Conflict-Free Diamonds

In the 1990s, concerns arose that some African diamond mines supported rebel movements undermining legitimate governments. The U.S. and 79 other countries agreed to a set of rules called the Kimberley Process to ensure that diamonds sold within their borders are “conflict-free,” meaning they do not come from mines supporting rebel activity, according to this definition.

Some organizations like the Anti-Slavery Society and the Responsible Jewellery Council are working to raise awareness of issues not addressed by the Kimberley Process, such as harmful environmental practices or child labor in diamond production. Interested consumers should ask retailers about their involvement with these efforts.