Gemstone Guide

In this section, we introduce the Four Cs of gemstone grading: color, clarity, cut, and carat (weight) as your buying guide when you’re on the market for purchasing the best value gemstones for your engagement rings, wedding rings, earrings and other jewelry. The Gemological Institute (GIA) and professional gemologists grade gemstones based on these properties. This buying guide will also touch on gem enhancements (like gem sparkle and light), quality, style and gemstone care without having to go to a professional jeweler, thus easing your budget.

Gemstone Education

From soft pastels to deep jewel tones, every gemstone tells a story. But there is more to gemstones than color. Our gemstone buying guide will allow you to discover the world of gem types, styles, gemstone shapes and the key quality factors to consider when making a gemstone purchase.

If you’re in the market for gemstone jewelry, you can find a wide selection at reputable online jewelers like James Allen and Blue Nile.

Gemstone Education To learn more on Gemstone Jewelry

Gemstone Types

In the gemstone jewelry industry, there is a universe of gemstone jewelry beyond diamonds. Each has its own unique history, characteristics, quality, gemstone color, depth, hardness and gemstone durability and value. It is important to know about these elements when you are in the market for the purchase of quality graded gems before purchasing from the store.

Colored Gemstones

Gem Cut

Gemstone Cuts

The skill with which a gemstone is cut determines its brilliance. Smooth quality cutting treatments can maximize the natural beauty of a gemstone while minimizing its flaws, turning it into an expensive gemstone.

Gemstone Colors

In the jewelry industry, GIA gemstone buying guides, the most important criteria in colored gemstones (and treated gemstone) valuation for a grading report by gem professionals, gem color is broken down into three attributes: hue, tone, and light saturation. These attributes, natural or resulting from treatment, combine to create the jewelry stone color we perceive and color will vary depending on the gem variety. These are important to know since colored gemstones are the favored betrothal ring presents among royalty. (Think- Princess Diana’s iconic sapphire ring!).

Gem Color

Gem Clarity

Gemstone Clarity

Most gemstones contain microscopic flaws called inclusions, which can affect brilliance, color, and overall gems appearance when graded in a lab report, even the budget. Clarity describes the degree to which these imperfections are present in the jewelry, whether natural or from treatments and how these will look when worn.

Gemstone Carat Weight

Not to be confused with size, carat refers to a gemstone’s weight. Because different gemstones have differing densities, two gemstones of the same carat weight can be very different sizes. The carat weight is the common determinant of the purchasing budget.

 Gem Carat

Gem Enhancement

Gemstone Enhancements

Gemstones are sometimes heat-treated to enhance their color, clarity, and durability. For instance, heating is a common treatment used to improve the appearance of a sapphire gem.


Not all gemstones can be cared for in the same way. Especially when worn often, it is important to learn how to properly care for your gems jewelry to help preserve its beauty and extend its lifetime.

Small Gemstone Care

Frequently Asked Questions

What is a gemstone?

A gemstone is a naturally occurring mineral crystal that will have formed over millions of years. When cut and polished, they are frequently used in jewelry. Some organic materials which are used in jewelry can sometimes be referred to as “gemstones,” although strictly speaking, this is incorrect.

What are precious gems?

A gemstone is a piece of mineral crystal and when cut and polished, can be used in gemstone jewelry. Precious stones rarer than diamonds are: The Intense violet-blue hues of tanzanite, the bright electric green of imperial jade- jadeite, alexandrite from Russia’s Ural Mountains, brightly saturated blue-green hues of paraíba tourmaline, iridescent ammolites, soft velvety, saturated blues of Kashmir sapphires, natural pearl, the red variety of beryl, and dark to saturated sapphire blue of the benitoite gem.

What is the rarest gemstone?

The rarest gemstone is Painite which was first discovered in 1951, and recognised as a mineral in 1957, by a British gemologist called Arthur Charles Davy Pain. Extremely rare, for many years there was only one example of this dark red crystal, and it was on display in the British Museum in London.

How are gemstones made?

Many minerals form beautiful crystals, but the most prized of all are gemstones. For example, diamonds are made up of carbon atoms which are the hardest natural substance found on Earth. Rubies are formed of a mineral called corundum, comprised of aluminium oxide and a mineral called beryl is responsible for forming emeralds which is a result of a complex mix of beryllium, aluminium, silicon, and oxygen.

How to tell if a gemstone is real?

Real gemstones are becoming increasingly difficult to identify due to the increased quality of synthetic stones. An expert will check the smoothness of the surface with natural stones having a slightly rough texture. They will also check the malleability (hardness) of the stone and its hue against detailed, official descriptions of different minerals.

Why are gemstones valuable?

Gemstones are nature’s gifts that form in the earth. They can only be extracted via mining which can be an expensive operation. As natural gemstones are becoming more scarce, their value is increasing.

What is the most valuable gemstone?

Gemstones that are considered most valuable are Tanzanite, Black Opal, Musgravite, Red Beryl, Alexandrite, Emerald, Ruby and Diamond.

How much are gemstones worth?

You will see in the gemstone buying guide that there is no set price range for colored gemstones. Prices may vary depending upon the quality and other factors. For Ruby, Emerald and Sapphire gems, as the quality and size of the gems increase, so too does the cost, as a buying guide will reveal.

How to identify gemstones?

Have a look at the different aspects of the gem, such as the color, clarity, size, hue, tone and cut shape to categorize your stone. See our guide to gemstone colors. Check the GIA’s colour wheel with 31 hues to narrow down your options.

Where are gemstones found?

Gemstones are naturally occurring mineral crystals that will have formed since ancient times in the crust of the earth. They need to be extracted through a mining process.

Are gemstones expensive?

Yes, you will see in the buying guide that they can very extremely expensive, especially rare stones like Tanzanite, Black Opal, Musgravite, Red Beryl, Alexandrite, Emerald, Ruby and Diamond.

Do gemstones expire?

Gemstones do not have an expiry date.

What is the most expensive stone?

Rare gemstones like the red diamond can fetch over $1 million per carat and there are less than 30 red diamonds found in the world.

What is the most expensive birthstone?

The April birthstone of a diamond is the most expensive stone.

How do I know my birthstone?

The practice of assigning birthstones goes back to biblical times. It is believed that the 12 gemstones on the breastplate of Aaron are consistent with the 12 tribes of Israel. But in the 1st and 5th centuries CE, these gems were linked to the zodiac signs.
Here is the birthstone guide, in both the traditional and modern lists:
January – Garnet. The garnet is both traditional and modern January birthstone
February – Amethyst. Amethyst is also in the traditional and modern list.
March -Aquamarine. In the modern list, it is aquamarine, while bloodstone is the March traditional birthstone
April – Diamond, in both traditional and modern lists.
May – Emerald, likewise listed in the traditional and modern.
June – Pearl in the traditional list. In the modern list, the pearl has been replaced by gem world newcomer alexandrite.
July – Ruby, in both the traditional and modern lists.
August – Sardonyx in the traditional list. Peridot in the modern list. Recent listing shows the spinel as an option to the peridot as the modern August birthstone.
September – Sapphire, in both traditional and modern listings.
October – Opals in the traditional list and tourmaline in the modern list. The tourmaline has many varieties. There are also multicolored tourmaline stones.
November – Topaz is both the traditional and modern November birthstone, but recently Citrine is a modern option.
December – Traditionally, turquoise and lapis lazuli while modern listing shows tanzanite, blue topaz and blue zircon as alternatives.

What should I know when buying colored gemstone jewelry?

Some tips from popular gem and jewelry companies:
Treated gemstones are not “fake” and are different from synthetic gemstones. …
There are many types of treatments specific to the type of gemstone. …
Treated stones are less expensive than untreated stones.
Natural, untreated gemstones are not always “the best.”
Nowadays, it is considered a safe practice to request a lab certificate for above $1000 purchase of ruby, sapphire, or emerald.

How can you tell a good gemstone?

The best or surest option would be to consult a gemologist for the quality of your gem. You can also look for cracks, scratches or black spots inside the stone – you can do this by passing a pen light across its surface. Also, observe color changes when the stone is in natural light, incandescent light and fluorescent light.

What is the difference between cabochons and faceted gems?

Opaque gemstones are usually made into cabochons (shaped and polished into a dome at the top and flat at the bottom). More transparent gemstones are mainly faceted. Cabochon cuts often vary in depth and proportions.
One gemstone that is rarely made cabochon is the diamond (especially for a ring) because faceting reveals its beauty in finely balanced proportions.