search
  • 登录
    注册
  • 只提供英语客户支持

    免费通话 - 仅限美国和加拿大:
    1-800-464-1640

    国际:
    +66-39303404

  • Change Language
  • USD

Heat Treatment


Centuries ago, someone stumbled upon the magical effect of applying heat to gemstones. High heat, such as that from a charcoal fire, can make a bland looking gemstone change its color into something spectacular. If this fortunate technique was not discovered, there would be very few affordable gemstones of good color on the market.

Heated Orange Sapphire
Heated Orange Sapphire

Heat treatment is considered to be a natural type of enhancement as it is a continuation of the processes that occur in the earth when the stone was originally formed. During treatment, the stone is heated to very high temperatures (approximately 1600 Celsius) causing inclusions, chemical elements, and other impurities to reform themselves and change the color of the stone. This color change may result in the stone being darker, lighter, more intense or of a different color. An example of this is the dissolving of rutile silk inclusions in blue sapphires, which improves both clarity and color. This heat treatment is permanent and irreversible.

Another example is ruby. This is a stone that is commonly heat treated. Only the most valuable and expensive rubies possessing the richest colors are not heat-treated. Ruby is heated almost to its melting point, allowing the aluminum oxide in the stone to reform, creating a new crystal structure. This allows the chromium in the stone to combine with different atoms, allowing for a better red hue. The same can apply to a type of sapphire known as gouda sapphire. These milky white sapphires turn blue, and account for many of the quality sapphires on today's market.

Detection of heat and diffusion treatment is possible because these treatments modify natural inclusions. The destruction of gas or fluid inclusions or the dissolving of mineral inclusions are clues to heat treatment. For gems that contain rutile needles, the needle margins may become diffuse. On rubies, inclusions may be found that are glassy in appearance. These are caused by borax-based substances that are used in the heat treatment process.

It is usually more difficult to find out if a stone has not been treated than if it has. Unadulterated stones can be harder to verify. However, there are some clues that can help. For example, gemologists can examine the inner workings of the stone and study the inclusions for signs of heat treatment. For example, if the stone has been treated, tiny inclusions such as small crystals will melt during the heat treatment process. A gemologist can easily see this using a microscope. An absence of such evidence could suggest an untreated stone.

Centuries ago, men sitting in front of charcoal fires were the first practitioners of the art of heat treatment. They would use pieces of bamboo to blow air into glowing charcoal where a few stones were placed, in an attempt to coax some new colors into their stones. Today, the technology is much more sophisticated, with professionals using large computer controlled electric furnaces. The old, crude methods are gone, but the result is still the same; drab gemstone are turned into something beautiful. This allows us all to have the chance to own a colored gemstone that we can be proud to show.

Amethyst, citrine, ametrine, aquamarine, tourmaline, topaz, light green tourmaline, sapphire, ruby, tanzanite, and blue zircon are gemstones that are typically color-enhanced by heat treatment. Here is a full list of the more commonly heated stones and how heat treatment enhances them.

Amethyst - lightens the color and will change the color of pale amethyst to "yellow" that will be sold as citrine.

Aquamarine - removes the greenish undertones that are common in this stone to produce a more blue stone. Also deepens the color.

Citrine - often produced by heating varieties of quartz.

Kunzite - to improve color.

Morganite - heat treatment changes the color from orange to pinkish.

Ruby - heat treatment improves color, removes iron stains, dissolves inclusions and fills tiny cracks.

Sapphire - to lighten or intensify color and to improve the uniformity of the color.

Tanzanite - to produce a more desirable blue shade.

Topaz - when used with irradiation, heat treatment will produce shades of blue. Also done to produce a pink topaz.

Tourmaline - to lighten darker shades of tourmaline. This is usually done with the green and blue varieties.

Zircon - to produce red, blue, or colorless stones.

  • 首次发布于: November-08-2006
  • 最后更新于:: January-17-2019
  • © 2005-2021 GemSelect.com版权所有。
    未经GemSelect.com(SETT Company Ltd.)的书面同意,严格禁止复制(文字或图形)。.
More Shapes
人气宝石
  • 蓝宝石
  • 祖母绿
  • 红宝石
  • 海蓝宝
  • 锆石
  • 蛋白石
  • 黄玉
  • 碧玺
  • 石榴石
  • 紫水晶
  • 黄水晶
  • 坦桑黝帘石
全部宝石 (139)
C D G H N P Q S
  • Cat's Eye Opal
  • Druzy Amethyst
  • Grandidierite
  • Hyalite Opal
  • Nuummite
  • Pyrite
  • Quartz With Marcasite
  • Scolecite
  • Spectrolite
  • 中长石拉长
  • 卢比莱碧玺
  • 变色宝石
  • 变色水铝石
  • 变色石榴石
  • 变色萤石
  • 变色蓝宝石
  • 坦桑黝帘石
  • 堇青石
  • 天河石
  • 孔雀石
  • 尖晶石
  • 巧克力蛋白石
  • 帝王黄玉
  • 异极矿晶簇
  • 彩虹月长石
  • 彩虹黄铁矿
  • 彼得石
  • 拉利玛
  • 拉长石
  • 摩西西
  • 斑彩石
  • 斑晶蛋白石
  • 方柱石
  • 方钠石
  • 日光石
  • 星光宝石
  • 星光日长石
  • 星光月长石
  • 星光柠檬石英
  • 星光石榴石
  • 星光粉晶
  • 星光红宝石
  • 星光蓝宝石
  • 星光透辉石
  • 月光石猫眼
  • 月长石
  • 枝状玛瑙
  • 查罗石
  • 榍石
  • 橄榄石
  • 沙弗莱石榴石
  • 海蓝宝
  • 火玛瑙
  • 火蛋白石
  • 猫眼宝石
  • 猫眼方柱石
  • 猫眼海蓝宝石
  • 猫眼磷灰石
  • 玉宝石
  • 玉髓
  • 玛瑙
  • 玛瑙晶洞
  • 珊瑚
  • 珊瑚化石
  • 珍珠
  • 珍珠母
  • 电镀黄玉
  • 石榴石
  • 石英
  • 石英猫眼
  • 砂金石
  • 砾背蛋白石
  • 硅孔雀石
  • 硅硼钙石
  • 硅线石
  • 硅线石猫眼
  • 碧玉
  • 碧玺
  • 磷灰石
  • 磷鋁石
  • 祖母绿
  • 符山石
  • 紅寶黝簾石
  • 紫水晶
  • 紫锂辉石
  • 紫黄晶
  • 红宝石
  • 红柱石
  • 红榴石
  • 红玉髓
  • 红纹石
  • 绿松石
  • 绿柱石
  • 绿玉髓
  • 绿龙晶
  • 缟玛瑙
  • 翡翠
  • 芙蓉石
  • 草莓石英
  • 菱锌矿
  • 萤石
  • 葡萄石
  • 蓝宝石
  • 蓝晶石
  • 蓝铜矿晶
  • 虎眼石
  • 虎眼石斑晶
  • 蛇纹石
  • 蛋白石
  • 蛋白石二层石
  • 血石
  • 赤铁矿
  • 金发晶
  • 金绿柱石
  • 金绿玉
  • 钙铁榴石
  • 钙铝榴石
  • 钙铝榴石
  • 钠柱晶石
  • 钻石
  • 铁铝榴石
  • 铬云母红宝石
  • 铬透辉石
  • 铯绿柱石
  • 锆石
  • 锰铝榴石
  • 镁铝榴石
  • 闪锌矿
  • 阳起石猫眼
  • 雪花黑曜石
  • 青金石
  • 顽辉石
  • 马拉亚石榴石
  • 马里石榴石
  • 鹰眼石
  • 黄水晶
  • 黄玉
  • 黑曜石
  • 黑蛋白石
Main Categories
  • 新品
  • 批量宝石
  • 标准化宝石
  • Gemstones By Piece
  • 高档宝石
  • 匹配的成对宝石
  • 凸面宝石
  • Drilled Gems, Briolettes and Beads
  • 诞生石
  • 宝石雕刻
  • 别致的宝石
  • 星光宝石
  • 未经加热处理的蓝宝石
只提供英语客户支持

免费通话 - 仅限美国和加拿大:
1-800-464-1640

国际:
+66-39303404

省钱
其他商品不收取额外的运费!
8.90美元全球发货

Update Translation
 
Current Value
New Value
GemSelect Gemstones
X 关闭窗口
Colored Gemstones
X 关闭窗口
Colored Gemstones
X 关闭窗口
Colored Gemstones
大小和重量

Gems are always measured in Millimeter (mm)

Dimensions are given as;
length x width x depth,
except for round stones which are;
diameter x depth

Select gems by size, not by weight!
Gem varieties vary in density, so carat weight is not a good indication of size

Note: 1ct = 0.2g

Size Comparison Chart