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

Diamond and Graphite

Diamond and graphite are both crystalline forms of the element carbon. Based on this fact, one would think they would be similar in many ways. But in fact they are very different. This highlights some important facts about crystals.

Both diamond and graphite have a very simple chemical composition; they are both pure carbon. Yet diamond is the hardest mineral known to man (10 on the Mohs scale), and graphite is one of the softest (less than 1 on the Mohs scale). As a result, diamond is the ultimate abrasive, whereas graphite is an excellent lubricant. Diamond is an electrical insulator while graphite is a good conductor of electricity. Diamond is usually transparent, but graphite is opaque.

Diamond and Graphite Structure
Diamond and Graphite Structure

Diamond is obviously far more valuable than graphite. Graphite is so inexpensive that it is used to make pencil lead. Nonetheless graphite is as interesting a material as diamond in many ways. Graphite is the high-strength component of composites that are used to build automobiles, aircraft, high-tech golf club shafts and tennis racquets.

But why is diamond so hard and graphite so soft? Also, if graphite is so soft, how can it be used as a high-tech material for golf club shafts and aircraft?

The answer lies in the different atomic structures of diamond and graphite. Graphite forms in layers or sheets where the carbon atoms have strong bonds on the same plane or layer, but only weak bonds to the layer above or below. The carbon atoms in diamond, on the other hand, have strong bonds in three dimensions. In diamond, the atoms are very closely packed and each atom is connected to four other carbon atoms, giving it a very strong and rigid structure in three dimensions.

In the case of graphite, only the bonds between the graphite layers are weak. This means that when the layers or sheets are rolled up into fibers, and those fibers are twisted into threads, the true strength of the bonds becomes apparent. The threads are molded into shape and held in place by a binder such as an epoxy resin. The resulting composites have some of the highest strength-to-weight ratios of any materials.

The differences between diamond and graphite highlight the importance of crystal structure to the properties of a gemstone. For example, all gems that have a cubic crystal habit, where the crystal structure is completely symmetrical, have an important property in common. Cubic solids refract light in all directions at the same velocity. So even though diamond, garnet and spinel have quite different chemical compositions, they are all singly refractive because of their similar crystal structure. Other less symmetrical crystal groups are doubly refractive, including orthorhombic, monoclinic and triclinic, all of which have specific internal symmetries and axes that dictate how light bends as it enters the crystal.

  • 首次发布于: July-24-2008
  • 最后更新于:: January-22-2019
  • © 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 (142)
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
  • 斜硅镁石
  • 方柱石
  • 方解石
  • 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
  • 烟晶
  • 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
  • 绿玉髓
  • 绿龙晶
  • 缟玛瑙
  • 翠绿锂辉石
  • 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