DAG779
Name of a meteorite.
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Damburite: Ca2(Fe,Mg,Mn)Al2(OH.BO3.Si4O12)
Etymolgy: name coming form the localty of discovery: Danbury - Connecticut USA.
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Dar al gani 319
Name of a meteorite.
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Datolite: ダトー石 Ca2 B2 Si2 O8 (OH)2
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Demantoid: デマントイド
A green garnet. The rarest of the garnets.
See Garnet.
Diamond: Berlian, Deimantas, Diamant, Diamante, Diament, Dimants, Elmas, Gyémánt, Intan, Kim cương, Timantti, Алмаз, ダイヤモンド.
C (Pure carbon).
From the Greek « adamas » = invincibility. The evaluation of a diamond is based on four criteria, commonly referred to as « the 4 C’s » :
Color,
Clarity,
Cut,
Carat.
In a perfectly cut diamond, there is a direct correspondance between the diameter of the stone and it’s weight (carat).
Below is a table of the weight of round brilliant cut diamonds, based on their diameter.
| mm | carat | mm | carat | mm | carat |
| 1.0 | 0.005 | 3.1 | 0.11 | 4.8 | 0.40 |
| 1.3 | 0.01 | 3.2 | 0.125 | 5.0 | 0.50 |
| 1.5 | 0.015 | 3.3 | 0.14 | 5.4 | 0.60 |
| 1.7 | 0.02 | 3.4 | 0.15 | 5.5 | 0.63 |
| 1.8 | 0.025 | 3.5 | 0.16 | 5.6 | 0.65 |
| 1.9 | 0.03 | 3.6 | 0.17 | 6.0 | 0.75 |
| 2.1 | 0.035 | 3.7 | 0.18 | 6.4 | 0.95 |
| 2.2 | 0.04 | 3.8 | 0.20 | 6.5 | 1.00 |
| 2.4 | 0.05 | 3.9 | 0.22 | 7.5 | 1.50 |
| 2.6 | 0.06 | 4.0 | 0.24 | 8.0 | 2.00 |
| 2.7 | 0.07 | 4.2 | 0.30 | 9.0 | 2.50 |
| 2.8 | 0.08 | 4.4 | 0.33 | 10.0 | 3.50 |
| 2.9 | 0.09 | 4.5 | 0.35 | 10.4 | 4.00 |
| 3.0 | 0.10 | 4.6 | 0.38 | 11.2 | 5.00 |
Diamond is a metastable form of carbon under normal temperature and normal pressure conditions. In it’s natural state, diamond has a cubic structure with centered faces and 8 atoms per conventional lattice. The structure of a diamond is the result of covalent bonds (the strongest form of chemical bonding, where the atoms share electrons) and is directional. Each atom is linked in all directions to it’s four closest neighbors in a tetrahedral geometric pattern. 
Diamond will only burn in pure oxygen and at very high temperatures.
Diamond has a high thermal conductivity, between 1000 and 2600 W/(m•K), while it’s electrical conductivity is low.
Diamond exists in a large variety of colors. The rarest are red, pink and blue.
All of the diamonds for sale on "gemfrance" were acquired from legitimate sources who are not involved in conflict financing, in conformity with the UN resolution concerning conflict diamonds. We guarantee that these diamonds were not mined in a conflict zone, guarantee based on our direct knowledge or on written guarantees from the sources from whom they were purchased.
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Black diamond
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Diaspore: Diaspor, Diáspora, Diaspoor, Diasporo, Діаспор, ダイアスポア, 硬水鋁石.
Al O (OH)
Synonym of Tanatarite.
Etymology: from the Greek "DIASPORE" = to scatter, because it cracks when heated at high temperature. Discovered by the French mineralogist Hauy in 1801.
First discovered in: MRAMORSKOI, KOSSOIBROD, URAL MOUNTAINS, RUSSIA.
A major source of aluminium. It’s composition (Aluminium Hydroxide) is intermediate between bauxite (another important source of aluminium ore) and corundum (the family of sapphire and ruby).
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Diopside, Diopsid, Diopsidi, Diópsido, Diopsied, Diopsyd, Diopszid, Диопсид, 透輝石, דיופסיד
Formule chimique: CaMg
Dioptase: Cu+2 SiO2 (OH)2
Etymology: from Greack "Diopteuin" = to see threw;
First publication : 1797
Author :
HAUY
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Disthene:
Synomym of Cyanite or Kyanite.
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Dolomite: Ca Mg (CO3)2
Etymology: from the French geologist DEODAT de GRATET de DOLOMIEU (1750-1801 )
Discovery: 1792 by Saussure in Tyrol - Italia.
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Dunilite (Mg,Fe,Mn)2SiO4 
Long mistaken for green peridot, dunilite was identified in 2000 as a new gem variety from olivine group, by Dunil Palitha Gunasekera (Sri Lanka).
It is an orthorhombic , magnesium, iron, manganese silicate. Though the x-ray diffraction pattern shows that the line spacing is similar to peridot . These spacing , however are not identical with those for peridot( By Dr Mary L Johnson , GIA July 8 1998).
This gemstone is only coming from "Katukubura montains", Kolonne, Sri-Lanka.
