Understanding Gemstones

Qualifying a Gem

There are over two hundred recognised gemstones. Most are minerals and are cut from naturally occurring crystals. To qualify as a gem, the specimen should be hard and tough to resist scratching and have beautiful clarity, colour or fire. Value is based on rarity and rare quality.

The most precious

Are Diamond, Emerald, Sapphire, Ruby and Red Coral. Diamonds are the most popular precious stone. While they come in a variety of shapes and sizes, they are judged by cut, colour, clarity and carat. Emeralds are a rare variety of the mineral beryl. They are green in colour because of their high chromium content. Sapphires are one of the hardest stones on the planet; second to diamonds. The value of Ruby is determined by its colour. The brightest and best ruby is known as the ‘Pigeon Blood Red’. Red Coral is often referred to as the ‘garden of the sea’. Initially it was thought to be a plant, later however, a scientist had discovered that these stones contain living animals, called polyps.

Buying gemstones from an Auction House

Auction houses are diverse markets. Unlike retail, where a lot of jewellery is standardized in design, jewellery and gemstones found in Auction Houses have uniqueness not found anywhere else. These pieces often hold significant history and their styles may be discontinued or entirely one-off. At Pfeffers, we are committed to helping you find your treasure. Be sure to contact us today for a free consultation!

Understanding Colour

The jewellery industry recognizes the highest quality gemstones by purity of their hue, the depth of tone, and the color saturation. The best value is in colours that include slight traces of other colors, are not too light or dark, and have a lot of saturated colour. Nearly all gemstones today, have been treated to enhance their colour. The most common methods of treatment are heating, nearly always seen with aquamarine, citrine, amethyst, sapphire, ruby and tanzanite, bleaching commonly seen with pearls, and irradiation performed on nearly all blue topaz.

Hue

The most valuable gemstones are those that exhibit a pure colour and only slight hues of other colours in addition to their primary colour. For example, sapphires range in hue from slightly purplish blue to slightly greenish blue, pink sapphires always range from pink to slightly purplish pink, and rubies range from slightly orange red to slightly purple red. With the exception of opals.

Tone

Tone represents the depth of colour, ranging from colourless to black. Gemstone tone is described as light, medium light, medium, medium dark, and dark.

Saturation

Saturation, or colour purity, refers to the degree to which the gem is free from brown or gray hues. The most desirable gemstones, which show little gray or brown, are often described as having vivid or strong colour saturation.

Clarity

Almost all gemstones contain inclusions. Even those most highly prized have at least some inclusions. Flawless gemstones are very rare and very expensive. The best value is found in gems that are lightly to moderately included. Emeralds are typically treated with colorless oil, wax or resin to minimize surface-reaching inclusions.

Identifying Marks

Gemstones form under unique circumstances, each individual gemstone is comprised of a combination of trace minerals. Which create a unique set of identifying marks or inclusions. Inclusions will not necessarily detract from the beauty or desirability of a colored gemstone.

What to Look For

When considering a coloured gemstone’s clarity, you should measure your expectations against the standard for that variety of gemstone. Some varieties of coloured gemstones, such as aquamarine, blue topaz, and citrine, have naturally fewer inclusions while other gemstones, such as emerald and ruby, tend to have a higher rate of acceptable inclusions.
Clarity is an important factor in comparing quality colored gemstones. Even opaque opals can have milky inclusions that will affect their iridescence and color play. In general, the best values are available in gemstones that are moderately included. Exceptional gemstones with few or no inclusions are available, but they can command extravagant prices.

Cut

Unlike diamonds, with gemstones there isn’t an ideal cut geometrically configured for maximum brilliance. A high quality gemstone cut is one that presents the most even colour, exposes the fewest inclusions, and displays the majority of the gemstone weight when set in jewellery. Coloured gemstones are generally cut to maximize the beauty of their colour. To recognize quality in the cut of a gemstone, there are several points to consider.

What to Look For

A good cut showcases the gemstone’s colour, diminishes its inclusions, and exhibits good overall symmetry and proportion. Gemstone colour can vary, there are no hard geometrical standards when it comes to maximizing brilliance or colour. Gemstones, especially rarer ones, are sometimes cut for size without regard for their colour. An example is when corundum varieties such as sapphire and ruby are cut for maximum weight rather than beauty, they may display banded colours or streaks.

Understanding Colour

The jewellery industry recognizes the highest quality gemstones by purity of their hue, the depth of tone, and the color saturation. The best value is in colours that include slight traces of other colors, are not too light or dark, and have a lot of saturated colour. Nearly all gemstones today, have been treated to enhance their colour. The most common methods of treatment are heating, nearly always seen with aquamarine, citrine, amethyst, sapphire, ruby and tanzanite, bleaching commonly seen with pearls, and irradiation performed on nearly all blue topaz.

Hue

The most valuable gemstones are those that exhibit a pure colour and only slight hues of other colours in addition to their primary colour. For example, sapphires range in hue from slightly purplish blue to slightly greenish blue, pink sapphires always range from pink to slightly purplish pink, and rubies range from slightly orange red to slightly purple red. With the exception of opals.

Tone

Tone represents the depth of colour, ranging from colourless to black. Gemstone tone is described as light, medium light, medium, medium dark, and dark.

Saturation

Saturation, or colour purity, refers to the degree to which the gem is free from brown or gray hues. The most desirable gemstones, which show little gray or brown, are often described as having vivid or strong colour saturation.

Clarity

Almost all gemstones contain inclusions. Even those most highly prized have at least some inclusions. Flawless gemstones are very rare and very expensive. The best value is found in gems that are lightly to moderately included. Emeralds are typically treated with colorless oil, wax or resin to minimize surface-reaching inclusions.

Identifying Marks

Gemstones form under unique circumstances, each individual gemstone is comprised of a combination of trace minerals. Which create a unique set of identifying marks or inclusions. Inclusions will not necessarily detract from the beauty or desirability of a colored gemstone.

What to Look For

When considering a coloured gemstone’s clarity, you should measure your expectations against the standard for that variety of gemstone. Some varieties of coloured gemstones, such as aquamarine, blue topaz, and citrine, have naturally fewer inclusions while other gemstones, such as emerald and ruby, tend to have a higher rate of acceptable inclusions.
Clarity is an important factor in comparing quality colored gemstones. Even opaque opals can have milky inclusions that will affect their iridescence and color play. In general, the best values are available in gemstones that are moderately included. Exceptional gemstones with few or no inclusions are available, but they can command extravagant prices.

Cut

Unlike diamonds, with gemstones there isn’t an ideal cut geometrically configured for maximum brilliance. A high quality gemstone cut is one that presents the most even colour, exposes the fewest inclusions, and displays the majority of the gemstone weight when set in jewellery. Coloured gemstones are generally cut to maximize the beauty of their colour. To recognize quality in the cut of a gemstone, there are several points to consider.

What to Look For

A good cut showcases the gemstone’s colour, diminishes its inclusions, and exhibits good overall symmetry and proportion. Gemstone colour can vary, there are no hard geometrical standards when it comes to maximizing brilliance or colour. Gemstones, especially rarer ones, are sometimes cut for size without regard for their colour. An example is when corundum varieties such as sapphire and ruby are cut for maximum weight rather than beauty, they may display banded colours or streaks.

Gemstone Cut

Look at the gemstone in the setting and ensure that all the facets are symmetrical. An asymmetrically cut crown indicates a gemstone of low quality. In all cases, a well cut gemstone is symmetrical and reflects light evenly across the surface, and the polish is smooth, without any nicks or scratches.

Size

The carat weight of a gemstone is not necessarily an accurate gauge for gemstone size. Viewing the gemstone from above, or the highest surface of the set stone is a variable view to gauge the size.

Densities

The carat weight of a gemstone does not necessarily allow you to accurately envision the size of the gemstone. Different gemstones have different densities, mass per unit volume, so two gems that appear to be the same size may actually have very different weights. A ruby is more dense than a diamond, therefore a 1-carat ruby will look smaller than a 1-carat diamond.

Enhancements

Nearly all gemstones on the market, have been treated to enhance their appearance. Gemstones that have not been treated but exhibit desirable colour and clarity command extravagant prices. Some enhancement treatments are almost universal, are permanent, and require no special care of the gemstone, such as heat treatment to enhance colour. Other treatments are common, and may require more or less special care to avoid damage, such as infusion of colorless oil, wax or resin to improve clarity.

Setting

Platinum

One of the most popular metals for engagement rings and wedding bands is platinum. Platinum’s naturally white sheen will never fade or change colour, and accentuates the sparkle and brilliance of a diamond. Platinum will last forever, making it the ultimate symbol for true, enduring, and everlasting love.

Gold

Gold has an extraordinary heritage with unique qualities. As an enduring element found naturally in a distinct yellow colour, gold is resistant to rust, tarnish, and corrosion. Although gold is very strong, it’s also the most malleable of all precious metals.

Silver

Fine silver is 99.9% pure silver. In this form the metal is beautiful and suffers from minimal tarnish, but it’s generally too soft and malleable for many uses, including making most silver jewellery. Instead fine silver is alloyed with copper to create sterling silver, which is 92.5% pure silver and 7.5% copper. This is why you will sometimes see sterling silver referred to as 925 silver.
The copper makes the silver harder, more durable and therefore much better to work with and use, but without compromising on colour. Most silver jewellery that you buy and wear will be sterling silver.