Recommended Diamond Grading Tools for Novices

Essential Diamond Grading Tools

To identify and grade diamonds, whether as a professional or hobbyist, you'll need tweezers, a loupe, a microscope, and the right lighting. Two other very important pieces of equipment you'll need are a spectroscope and a refractometer.

Purchase a Diamond Tester

The diamond tester is a simple electronic device that can distinguish between a natural diamond and a simulant. Generally speaking, they tend to provide accurate results regarding the authenticity of a diamond. However, there are exceptions. Since they rely on thermal conductivity, they may mistake a synthetic moissanite for a natural diamond. Let's explore this a little further.

How Does a Diamond Tester Work?

A diamond tester works by measuring the rate at which heat passes through a stone. This is thermal conductivity. If you place the tip of the tester on the stone, it will measure the thermal conductivity and give you an electronic reading. Recall that natural diamonds have very high thermal conductivity. (Their capacity to conduct heat is one reason they're used in manufacturing). Therefore, measuring thermal conductivity with a diamond tester works well for distinguishing between a natural diamond and a synthetic cubic zirconia (CZ), for example, since they conduct heat differently.

How Does a Moissanite Tester Work?

On the other hand, synthetic moissanite (a lab-created stone that resembles a diamond) conducts heat similarly to natural diamond. Therefore, there's a high likelihood a diamond tester will misidentify a moissanite.

You have some options. You can purchase a separate moissanite tester (which measures electrical conductivity, a property that may help distinguish moissanites from diamonds) or make sure you purchase a multi-tester. Such a device acts as both a diamond and moissanite tester. For professionals, this may make a worthwhile investment.

Do You Need a Moissanite Tester?

You can also conduct other gemological tests to help distinguish diamond from moissanite. For example, moissanites have birefringence and a uniaxial + optic character, unlike diamonds. You can test both these traits with a refractometer. Moissanites also have a lower specific gravity (SG) than diamonds.

Please note, a moissanite tester or electrical conductivity test won't help you distinguish a cubic airconia from a natural diamond.

Choosing Tools for Distinguishing Other Diamond Simulants and Synthetics

Many materials have been used to simulate or imitate natural diamonds, including some natural gemstones that may resemble diamonds, like white sapphires. This may help you choose which tools and tests to use.

Synthetic diamonds, actual diamonds created in laboratories, are still rare in jewelry, but you may encounter some during tests. Unfortunately, diamond testers won't help distinguish synthetic from natural diamonds.

For Grading Diamond Color, Purchase a Set of Master Stones

Without a set of master stones, grading diamond color will prove very difficult. You'll use this set to grade the color of other diamonds. A master stone set can consist of real diamonds or CZs. Your choice will likely depend on whether you're going the professional or hobby route.

Why Professionals Should Buy Natural Diamond Master Stones

We recommend that professionals purchase natural diamonds for their master stone set rather than CZs. You can easily find and read complaints about CZ masters on the internet. Some sets may have the colors of some or all the stones not quite right. The stone colors of some sets may even change over time. Issues like these will affect your ability to correctly grade diamonds.

If you're creating a diamond grading report for a client, you need to stand behind your assessment with full confidence. If a potential client asks whether you use natural diamond masters, you want to be able to say "yes." This could make the difference between winning or losing new business.

Buying or Building a Natural Diamond Masters Set

You can either purchase a complete set or build your own by sending diamonds to a gemology lab for grading as master stones. Please check with a lab, such as the Gemological Institute of America (GIA), and confirm their requirements for grading a diamond master stone before beginning to assemble your set.

We recognize that either choice represents a significant investment for a business, particularly for new professionals just beginning their careers. So, we asked some experts for advice on building a master set. Here's what we heard.

• Size matters :Your master stones should weigh at least 0.25 carats. The larger, the better, so you can see the colors.
• find a diamond dealer : The diamond trade is still a relationship-driven business. It may help if someone known in the trade can vouch for you. Let the diamond dealers know you're trying to build a master set and they may work with you on the price. You may even be able to receive a stone "on memo" while you wait for it to be graded by a lab. Thus, if the lab rejects it, you aren't obligated to buy the stone and can send it back.

  Newcomers may need to pay up-front to establish some credit with dealers. You establish credit in the diamond trade the same way as any other type of credit. You get people to make small bets on you and work your way up over time, leveraging the previous successful transactions to gain access to more credit and trust.

• think about resale : At the end of the day, you're purchasing diamonds, which have resale value. If you classify them as a business expense, they may be tax-deductible. (Check your local tax laws). 

  You might also save time by finding someone who's selling their masters. However, such opportunities are rare, and the price may not be right for you.

• buy strategically : Even if you buy one stone at a time, think about what colors you want to buy in what order. You'll need about 8 stones (color grades E-L) and aim for VS2 clarity. Perhaps start with a G and then move to a lower color, like a K. Then, go high again (E or F), then low (I).
• budget for lab fees : You need to send each stone to a gem lab to be graded specifically as a master. (Regular reports won't qualify). So, don't forget to budget for fees. Be aware that the GIA rejects most master stones it receives. Therefore, your budget should leave room for the possibility that you may need multiple tests before you find the right stone.

  You might also send each stone to another lab for a second opinion, so the stones become "double verified." Of course, you must budget for that, too.

• do you travel with your diamond masters? 

  If you're pursuing diamond grading professionally, consider whether you plan on traveling to customer sites. Ask your insurance company whether they'll cover your diamond master set as a tool. Some insurance plans may not cover diamond masters. In that case, what's your tolerance for risk? You might opt instead for CZ masters.

Choosing a CZ Masters Set

For the hobbyist, a 10-stone CZ master stone set will suffice. CZ sets have surged in popularity due to one obvious factor: the price. However, keep in mind the possible problems we've previously discussed regarding their colors. 

Look for a CZ set with a warranty and find out if you can send the set back to the manufacturer to be checked. You can also try keeping the CZ set in complete darkness to help prevent fading.
Because of the price differential, try to get a set with 1.0-ct stones. Even with CZs, size matters!