1749 Post Oak Blvd Houston, TX 77056 | Tel: 713.960.8950

Diamond Buying Guide

Why a Diamond?

Loose Diamonds

Diamonds are Beautiful

The reasons for buying diamonds are as different as the people who desire them. Through the years, diamonds have provided fulfillment for emotional and practical needs. They are sought after gifts, status symbols, tokens of romance, and even long-term investments. Most of all, the physical character of a diamond is unparalleled in the natural world and more unique than any other gemstone.

Diamonds are beautiful. Their exquisite beauty and mystic provides us with an outward expression of love. They create an aura of success and inspire feelings of distinction. Diamonds interact with white light better than any other gemstone, giving it fire and brilliance that dazzles the eye and provokes the heart.

Diamonds are Rare

Diamonds are rare. Although there have been new discoveries of gem diamond resources, the supply is still limited. It is a fact that larger diamonds are increasingly harder to find. When 250 tons of ore (mineral bearing rock) are blasted, crushed and processed, chances are there will only be one carat of rough diamonds recovered. Less than 20 percent of all rough diamonds are suitable for cutting into gem quality diamonds for jewelry.

Diamonds retain value. While diamond prices may fluctuate with economic conditions, even after years of being worn and enjoyed, a diamond retains value and can be passed from generation to generation.

Diamonds are Durable

Diamonds are durable. The word diamond is derived from the Greek “adamas,” which means “unconquerable”. This is fitting because diamonds are the hardest substance known to man. In fact, because of the hardness of this gem, the vast majority diamonds mined today are not sold to be manufactured into jewelry, but are utilized in industrial tool parts.

The Cs

Carat, Clarity, Color& Cut

The Four Cs are the key characteristics of diamonds: Carat, Clarity, Color and Cut. Taking a few minutes now to learn about them will make your purchasing experience smarter, easier and more enjoyable. At Zadok’s we have introduced two additional Cs: Certificate and Cost. With our expert advice, you will have the education and confidence you need to make this important decision.

More than 50 years ago, GIA created a universal standard for determining and describing diamond quality: the 4 Cs (Carat, Clarity, Color & Cut) and the GIA International Diamond Grading System™, which today includes the D-Z color scale, the Flawless-I3 clarity scale, and the Excellent-Poor cut grading scale. This standard is accepted by virtually every professional jeweler and used by every knowledgeable diamond buyer in the world.1

1 Provided by GIA




Diamonds and other gemstones are weighed in metric carats: one carat is equal to 0.2 grams, about the same weight as a paperclip. Don’t confuse carat with karat, as in “18K gold,” which refers to gold purity.

Just as a dollar is divided into 100 pennies, a carat is divided into 100 points. For example, a 50-point diamond weighs 0.50 carats.


Because diamonds are formed deep within the earth under extreme heat and pressure, they often contain unique birthmarks, either internam (inclusions) or externam (blemishes). Diamond clarity refers to the absence of these inclusions. Diamonds without these birthmarks are rare, and effect a diamond’s value.

Flawless (FL) – No inclusions or blemishes are visible to a skilled grader using 10x magnification. Exceptionally rare

Internally Flawless (IF) – No inclusions and only blemishes are visible to a skilled grader using 10x magnification

Very, Very Slightly Included
(VVSI and VVS2) – Inclusions are difficult for a skilled grader to see under 10x magnification

Very Slightly Included
(VSI and VS2) – Inclusions are clearly visible under 10x magnification but can be characterized as minor

Slightly Included (SI1 and SI2) – Inclusions are noticeable to a skilled grader using 10x magnification

Included (I1, I2, and I3) – Inclusions are obvious under 10x magnification and may affect transparency and brilliance


The most widely used color grading system is the one developed by GIA, which identifies colors with alphabetical letters ranging from D (colorless) to Z+ (a diamond with a light yellow or brownish shade). Stones with a grade from D to J are sometimes referred to as white diamonds.

Many of these color distinctions are subtle and are nearly invisible to the untrained eye. These slight differences make a difference in diamond quality and price. For example, the nuances of color are so fine between the grades that the average consumer cannot tell the difference between a D and F color. However, the price difference between D and F color diamonds many be as much as a 10% to 20%, depending on their size and clarity. The GIA color grading scale above applies only to white diamonds and not to fancy color diamonds.


Relative to its long history, only in modern times have cutters been able to successfully harness a diamond’s potential beauty. Today, cut is an essential factor in determining a diamond’s value. Cut is the factor that fuels a diamond’s fire, sparkle and brilliance. If the diamond cut too deep or too shallow, it will not reflect light nor fiery brilliance in the most optimal fashion.

In 2004, GIA unveiled a diamond cut grading system for standard round brilliants in the D-to-Z color range. This system, the product of intensive research and testing, assigns an overall diamond cut grade as one of the following: Excellent, Very Good, Good, Fair, Poor.

Beauty truly is in the eye of the beholder. The diamond shape you choose is a matter of personal preference. Zadok Jewelers carries many different shapes and sizes of stones. Your consultant will provide you with additional information to help you better decide which shape is best for you.

GIA – The Highest Quality

Zadok Jewelers offers and prefers the best GIA (Gemological Institute of America) Certified Diamonds. The Graduate Gemologists on the Zadok staff combine their education and vast experience to present diamonds that meet the criteria of our valued customers. We only select the best of the best.

GIA is an independent, nonprofit, gemological research and academic organization focused on the science of gemology and is internationally recognized as the world’s foremost authority in gemology™. Through research, education, laboratory services, instrument development, and communications outreach, GIA is dedicated to serving the public trust in gems and jewelry by upholding the highest standards of integrity, academics, science, and professionalism. GIA can be found on the web at www.gia.edu.2

2 Provided by GIA



A certificate thoroughly describes the quality of a diamond, but it does not place a monetary value on the gem. You will receive a complimentary appraisal with your purchase.

Staffed by expert diamond graders and gemologists, GIA laboratories set the standard for grading practices used worldwide. Known for its strict impartially and benchmark grading services, GIA is entrusted with grading and identifying more gems than any other lab, including some of the world’s most famous diamonds.3

Not all certificates are created equally. Because of their outstanding reputation of having the strictest standards, a GIA Certificate with your purchase is highly respected by your insurance company and solidifies your investment.

3 Provided by GIA

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