5 Carat Lab-Grown Diamonds

Choose a 5 carat stone by its cut and its measurements before its weight: a well-cut round is about 11.0 to 11.1 mm across, and one that measures noticeably less is carrying weight you cannot see. Set a top weight before you shop, because this page has no upper limit and each extra carat adds well under a millimeter of width. Once you buy, have the piece appraised for replacement value and scheduled on an insurance policy, since a grading report is not a valuation.

Every point of weight adds to the price, so a cutter working a large crystal has reason to keep weight rather than polish it away. Big stones are often cut deep, with a heavy pavilion, a thick girdle or proportions that favor the scale over the sparkle. A stone that only just reaches 5.00 carats deserves a second look: it may have been shaped to make the number rather than to return light.

On a round, the cut grade is the quickest test. On an IGI report, take the top of its scale, Ideal or Excellent, and pass over lower grades at this size, where a dull or glassy patch has a broad face to show on. A recent GIA report folds cut into one Premium or Standard rating, so for it, and for other shapes where a report carries no cut grade, look for Excellent or Very Good polish and symmetry where they are listed and, where there is one, judge the video. Our guide to how cut grades are decided explains the scale.

Above 5 carats the weight on the report tells you less about size than the measurements do, and what each line of a grading report records shows where to find them. A well-cut 5 carat round measures about 11.0 to 11.1 mm across. A 6 carat round is only about 0.7 mm wider, and doubling to 10 carats adds about 3 mm, to roughly 13.8 to 14.0 mm. Weight grows with the cube of the width, so each added carat buys less width than the last.

A 5 carat round that measures 10.7 mm is holding its extra weight below the girdle or in a thick edge, out of sight once set. At this weight, a few tenths of a millimeter can mean a quarter of a carat or more that you pay for and never see.

Decide on a top weight before you start. This page has no upper limit, and it is easy to drift up a few points at a time; past your number, spend on cut rather than carats. Prices tend to jump once a stone reaches 5.00 carats, yet one of 4.80 to 4.99 measures less than 0.2 mm narrower; those stones are on the 4 Carat page, so compare both sides of the line. Where the dated price table appears, its one row runs from 5.00 carats with no ceiling, so judge any price against stones close in weight.

A 5 carat oval runs about 13.5 by 10 mm and looks larger than a round of the same weight. An emerald cut of about 11.5 to 12 by 8.5 mm gives broad, slow flashes that keep a big stone calm on the hand, while a radiant keeps the rectangle and adds a brilliant's sparkle. A cushion of about 9.4 to 9.7 mm a side faces up smaller than a round of the same weight, since many are cut deep, and it has no sharp corners to guard.

On a size 6 finger, about 16.5 mm across, a 5 carat round covers roughly two thirds of the width, and an oval set lengthwise about three fifths. Pears and marquises look larger still, about 15 by 9.5 mm and 17.5 by 8.5 mm, but at that length their points stand out, so have them held by V-prongs or a bezel and avoid an inclusion near a tip.

A grading report describes a diamond's weight, measurements and grades; it puts no value on it. To insure a stone this size, many insurers ask for an appraisal, a written valuation stating what it would cost to replace the piece, or accept a recent receipt, and then list it on the policy by itself, which is called scheduling. Unscheduled, jewelry is often covered only up to a low theft limit on a home or renters policy. The Journal covers how insuring an engagement ring works.

Have the finished ring appraised rather than the loose stone, and keep the grading report with the appraisal, since its measurements help identify the diamond. Review the appraisal every few years: replacement cost moves with the market, and lab-grown prices can fall as well as rise, so an old figure can leave you short of cover or paying for more than you need.

Where the dated price table appears on this page, it gives the median price per carat, in US dollars, for stones of 5.00 carats and up, as of the date beside it. Because the band has no upper limit, that figure mixes stones just over 5 carats with much larger ones, so treat it as a rough guide. Sort the grid by price and compare stones close in weight, shape and grades to the one you want.

A well-cut 5 carat round is about 11.0 to 11.1 mm across, roughly two thirds of the width of a size 6 finger, so it reads as a large stone from across a room. Long shapes look bigger still: an oval of the same weight is about 13.5 by 10 mm and a marquise about 17.5 mm from tip to tip. Depth moves every figure, so check the measurements on each report.

Not in itself, if the size suits your hand and you are happy to give it some care. A stone this large sits wider and often higher, so it catches on gloves, sweaters and bag linings more often. A low setting, a bezel or a shape with rounded corners makes it easier to live with. On a slim finger it covers most of the width; on a broad hand it looks more in proportion.

No. Clarity is graded at 10x magnification and color face down beside master stones, not on a hand. At 5 carats, take the lowest clarity that looks clean at normal size and the lowest color that looks white against your metal; in an emerald cut or Asscher, whose open steps show both, go a grade or two higher than in an oval or radiant. Beyond that, a better grade changes the report and the price, not the ring.

It should say the stone is lab-grown and name the grading lab and report number, along with any girdle inscription. It should also give the weight, measurements and grades, and describe the setting: metal, weight and any side stones. A valuation that leaves out the origin can price the ring as a natural diamond, and you would then pay premiums on cover a claim would not support.