Gemstone Color Alterations

Gemstones are frequently subjected to treatments to alter or enhance their color. Heat, radiation, dyeing and oiling are four of the more widely used procedures for altering a gem’s color. While this is a common practice, buyers should be advised when a stone has been treated.

Dyeing
Dyeing has been in practice for ages. Jade, chalcedony, coral, opal, lapis, emeralds, star rubies and star sapphires are all stones that are frequently dyed.

Heat
When heat is applied to some gemstones it can lighten, darken or completely change their color. The change is usually permanent. Jewelers have been using this process for hundreds of years, and most rubies and sapphires undergo heat treatments. A stone that has an excellent color and has not been subjected to heat treatment can command a higher price than one that has.

Heat is frequently used on these gemstones:

Amethyst – heat applied to amethyst can result in yellow or green stones
Aquamarine – heat can darken the shade of blue
• Sapphire – heat lightens the blue, can turn violet stones to pink, or deepen a pale color
Tanzanite – heat is used to produce brilliant blue tanzanite from a dull brown stone
• Topaz – heat produces pink or blue stones
Tourmaline – heat lightens the dark shades of tourmaline

Radiation
Like heat, radiation treatments can alter gemstone color. Color changes from radiation are not always permanent – it depends on the stone.

Radiation is sometimes used on these gemstones:

• Aquamarine – together with heat, radiation can darken the shade
Diamond – radiation can take the color from off-white to another color, like green
Sapphire – radiation can create gold colored sapphires
• Topaz – radiation takes the stone from clear to blue

Oiling
Oiling is used mainly on emeralds. Emeralds are prone to fine cracks which can appear as unattractive white lines. The oil fills these cracks so that the white is no longer apparent. The treatment usually lasts for years, however hot ultrasonic cleaners or organic solvents like gasoline or those in paint remover can remove the oil from the emerald. In such a case, the stone can be oiled once again.

Foil Backing
This is more of a caveat emptor-type thing. In some cases, where the gem is set into the gold, and the back is closed so that you can’t see the underside of the gem, colored foil is used beneath the gem to give it a richer color.

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Yellow Diamond Engagement Rings

More and more women are choosing colorful engagement rings. Some go for sapphire rings, some for emeralds, and some women are choosing the unique sparkle of yellow diamond engagement rings.

What are Yellow Diamonds?
Colorful diamonds result when impurities are trapped in the diamond while it forms. In the case of yellow diamonds, nitrogen was in the diamond while it formed, causing the yellow hue. Because of the prevalence of nitrogen, yellow diamonds are the most common of colored diamonds.

Types of Yellow Diamond Engagement Rings
Different types of yellow diamond engagement rings are available, and couples can choose rings where the yellow diamond is the primary stone, or rings that use yellow diamonds as accent stones. When the yellow diamond is the main stone, small round white diamonds or baguettes are frequently used to the sides of it. Alternatively, a couple can go with the traditional white diamond solitaire, with small yellow diamonds to the side. On the other hand, couples may choose to use channel-set white and yellow diamonds on the wedding band instead of the engagement ring.

Yellow Diamond Hardness
Regardless of color, diamonds are the hardest known gem, measuring a 10 on the mohs scale, a tool for comparing gem hardness. Because of this, diamonds are less prone to scratching, chipping and cracking than other gemstones. This makes yellow diamonds ideal for use in engagement rings, which may be worn every day of a woman’s married life.

Yellow Diamond Color
Some diamonds have just a touch of yellow color, while others are a strong banana yellow shade. Light yellow diamonds are sometimes referred to as Champagne Diamonds, while darker yellow diamonds are Canary Diamonds. All other properties being equal, darker yellow diamonds are generally more valuable than lighter.

Yellow Diamond Engagement Ring Metals
Yellow diamonds look stunning against white metals like platinum and white gold, particularly when combined with white diamonds. While the white metals are currently more fashionable, yellow gold and yellow diamonds can also make an attractive combination in an engagement ring.

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