Diamond

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April Birthstone

Ahh, diamonds. Everyone knows what diamonds are, but most might not realize what they once were--chunks of dark, nondescript carbon similar to charcoal, roasting and rumbling around deep within the earth. Fortunately, through eruptions and other harsh works of Mother Nature, diamonds eventually find their way to the surface for man to find, cut, polish, and enjoy. Talk about an ugly duckling turning into a swan! Named from the Greek word adamas, meaning "unconquerable", diamonds are renowned for their impeccable hardness and stellar brilliance and the birthstone for those born in April.

Diamond Polished
Diamond Classification
Common Name Diamond
Species Diamond
Diamond Optical Properties
Transparency Transparent - Opaque
Dispersion Strength: Moderate Fire Value: 0.044
Refractive Index Over The Limit 2.417-2.417
Optic Character NA
Optic Sign NA
Polariscope Reaction Singly Refractive (SR) With ADR
Fluorescence SWUV: Colorless: commonly inert or weak to strong blue but could be any color;Occasional phosphorescence of 30 seconds or less.Red stones: Inert to faint blue.Red Type II stones: inert to medium to strong orange.Blue Type IIb: rarely weak red to orange-red, occasionally blue to greenish blue and phosphorescence is blue to green and occasionally red to orange red.Blue Type IIa: sometimes weak to strong blue, greenish blue, green, yellow or orange.Orange, yellow and brown stones: Inert to faint blue.Gray or black stones: Inert to strong blue is usual but can be any color.
LWUV: Colorless: commonly inert or weak to strong blue but could be any color, generally a stronger reaction than under SWUV; Occasional phosphorescence of 30 seconds or less. Red Stones: inert to medium to strong blue.Red Type II stones: inert to medium to strong orange.Blue Type IIb: Inert.Blue Type IIa: sometimes weak to strong blue, greenish blue, green, yellow or orange.Orange, yellow or brown stones: inert, faint to moderate to strong blue.Gray or black stones: Inert to strong blue is usual but can be any color.
Pleochroism None
Diamond Characteristic Physical Properties
Hardness 10
Streak White
Specific Gravity 3.500-3.530 Range:+/-0.10 Typical:3.520
Toughness Good
Inclusions Diamonds can have naturals, naturals with trigons, bruted girdle surface if not faceted, bearding, sharp facet junctions, angular mineral inclusions, parallel growth marks, color zoning, internal graining. Natural pink diamonds show strong strain patterns when view using magnification and polarized light. Red stones often have uneven parallel bands of red or pink and blue stones have blue and colorless zones. Yellow stones might have yellow and brown graining parallel to octahedral crystal faces and might form a cross hatch pattern. Blue Type IIb diamonds are most often free of mineral inclusions, but sometimes can have opaque black inclusions; whiteish transparent graining. Blue Type Ia and IIa diamonds might display color zoning near can be located near surface of the stone close to radiation stains. Green stones often have large naturals because the color is sometimes confined to the surface due to natural radiation staining. Yellow or orange stones might blotchy yellow color zones that are darker at the center and have polish lines that are never oriented the same way on adjacent facets.
Luster Adamantine
Stability Excellent
Fracture Step-Like
Cleavage Perfect, in four directions
Diamond Chemistry & Crystallography
Chemical Name Carbon
Chemical Formula C
Crystal System Cubic
Chemistry Classification Native Element

Diamond Colors

  • Yellow Diamond Yellow
  • White Diamond White
  • Red Diamond Red
  • Purple Diamond Purple
  • Gray Diamond Gray
  • Black Diamond Black
  • Blue Diamond Blue
  • Brown Diamond Brown
  • Colorless Diamond Colorless
  • Green Diamond Green
  • Orange Diamond Orange
  • Pink Diamond Pink

Diamond Spectra

Diamond Spectra
DIAMOND

Color due to nitrogen. A strong diagnostic line in the violet at 415nm

Diamond Spectra
DIAMOND Greenish Blue Irradiated

Color due to artificial irradiation and annealing. Although mounted this blue diamond provided a spectrum in which some the absorption bands can be detected. The main feature is a strong absorption centered at 595nm. A faint narrow band is seen at 637nm. in the orange and a very weak narrow band at 503nm. in the blue-green area. Very little transmission is seen below 560nm. or above 670nm.

Diamond Spectra
DIAMOND (Treated)

Color due to irradiation and annealing. Absorption line in the orange which has not been reported in diamonds of natural color. With careful searching this can be seen here as an extremely faint narrow line at 594nm. Two other lines are also seen here at 498nm, and 504nm. in the blue- green area

Diamond Spectra
DIAMOND - Lab Grown

Color due to irradiation. Most of the red and orange with a little green is transmitted and a broad absorption band is centered at 560nm. Two weaker bands appear in the orange and another in the green. A little blue is transmitted before total absorption occurs at about 485nm. The distinguishing feature is the single prominent line seen here at 637nm

Diamond Spectra
DIAMOND

Color due to nitrogen. This light brown diamond shows the diagnostic line in the violet at 415nm. with an indication of other vague lines also close by

Jewelry Television acknowledges the significant scientific contributions of John S Harris, FGA to the study of gemstone spectra and with deep appreciation to him, acknowledges the use of his images and related notes about gemstones and their spectra in the educational materials on this website.

Countries of Origin

Tanzania, United Republic Of; Afghanistan; Argentina; Iran (Islamic Republic of); Multiple; United States of America (the); Congo (the); Thailand; India; Unknown; China; Brazil; Italy; South Africa; Australia; Germany

History

Let's face it - diamonds are the quintessential gemstone. They're a girl's best friend... the forever stone...Sure, diamond is the only gemstone composed of a single element - carbon. Sure, it's the hardest gemstone, measuring a 10 on the hardness scale, but that's not why we love diamonds. It's their sparkle, their promise... it's the white light that dances. It's the way they say you have arrived.

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Related Videos

More About Diamond

The ancient Greeks and Romans, who were clearly fanciful folks, thought that diamonds might be the tears of the gods, or that they were fragments of falling stars. Plato saw diamonds as living beings that embodied celestial spirits.

Sisk Gemology Reference

Showcasing 200 gemstones in over 1,000 pages and accompanied by more than 2,000 photos, The Sisk Gemology Reference is a must-have in every collector’s library. Each comprehensive, three-volume set features state-of-the-art photography, detailed illustrations, and scientifically precise descriptions to create an entrancing experience for gemstone amateurs and afficionados alike.

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Creation Method

Lab Grown-HPHT

High pressure, high temperature Lab Grown diamonds (HPHT diamonds) are produced in a way similar to synthetic flux grown gems, however, during the HPHT process, as the name implies, the growth chamber is exposed to high temperature and pressure. The diamonds then crystallize in a lower temperature section of the growth chamber. Colored diamonds can be produced in this way. Lab Grown gems have the same chemical, optical, and physical properties of their natural counterparts, but are a more cost-effective alternative to a natural gem.

Lab Grown-HPHT Diamond
Lab Grown-HPHT Classification
Common Name Lab Grown-HPHT
Lab Grown-HPHT Optical Properties
Fluorescence SWUV: Variable
LWUV: Variable
Lab Grown-HPHT Characteristic Physical properties
Inclusions Elongated or rounded opaque highly reflective inclusions of metallic flux that rarely might cause the stone to be slightly magnetic. There might be clouds and pinpoints of flux in Chatham blue material. There might be impurities that might show faint color zoning in cross-shaped or hourglass pattern. Darker red stones typically will show areas of color zoning with intersecting square or cross shaped yellow areas encompassed by red. Pink stones have pink and colorless zones and might show metallic inclusions with brown halos. Irradiated green stones might have even coloration.

Lab Grown-CVD

Chemical vapor deposition diamonds (CVD diamonds) are fairly uncommon. These Lab Grown Diamond gems crystallize from a chemical-rich vapor due to a chemical reaction that releases carbon atoms. These carbons atoms are then free to bond to a diamond seed plate where they form crystals. Lab Grown gems have the same chemical, optical, and physical properties of their natural counterparts, but are a more cost-effective alternative to a natural gem.

Lab Grown-CVD Diamond
Lab Grown-CVD Classification
Common Name Lab Grown-CVD
Lab Grown-CVD Optical Properties
Fluorescence SWUV: weak to moderate orange to yellow orange
LWUV: Inert to weak orange to yellow-orange.
Lab Grown-CVD Characteristic Physical properties
Inclusions CVD synthetic diamonds are often inclusion free but might contain pinpoint brown or black inclusions. The black inclusions might be graphite. If a seed crystal is present there might be flux inclusions from a HPHT diamond.

Enhancement

Laser Drilled

In light or colorless gemstones, dark inclusions are more easily seen than colorless ones, so a means of lightening dark inclusions was developed using lasers. In laser drilling treatments, a narrow channel is laser drilled from the stone's surface to the dark inclusion. Once the open channel has been created, a mixture of boiling acid is introduced under pressure and the inclusion is subsequently bleached or dissolved.

Laser Drilled Diamond
Laser Drilled Classification
Common Name Laser Drilled
Laser Drilled Optical Properties
Fluorescence SWUV: Variable
LWUV: Variable
Laser Drilled Characteristic Physical properties
Inclusions The stones will have laser drill holes that reach the surface and sometimes appear similar to wormhole like channels. The holes can be differentiated from natural etch channels because natural channels will have a geometric structure. Stones will have bleached white inclusions. If stones are glass filled they will display flash effect or interference color flash in darkfield lighting. Inclusions in these stones are typically trapped gas bubbles, cloudy or discolored material in fractures, crackled or web-like texture.
Stability Very Good

HPHT

HPHT is an acronym for a process using High Pressure and High Temperatures. In this high-tech treatment technique, diamonds are subjected to extremely high temperatures and high pressures using similar equipment to that in which diamonds are synthesized. The heat and pressure simulate conditions during a diamond's formation deep in the Earth, and can cause alterations in the diamond's crystal structure and resulting appearance, thereby improving or altering a diamonds color.

HPHT Diamond
HPHT Classification
Common Name HPHT
HPHT Optical Properties
Fluorescence SWUV: Variable
LWUV: Variable
HPHT Characteristic Physical properties
Inclusions Etched or pitted naturals or feathers, tension fractures sometimes containing graphite around crystalline inclusions.

Irradiated

Exceptional quality colored diamonds are rare and extremely expensive. However, naturally dark or tinted diamonds can be irradiated to create a more pleasing, uniform color. Modern irradiation practices leave diamonds vibrantly colored and non-radioactive, creating beautiful options for gemstone collecting and jewelry. Once a diamond has been irradiated it becomes very sensitive to heat, so jewelers need to take care when using a jeweler's torch.

Irradiated Diamond
Irradiated Classification
Common Name Irradiated
Irradiated Optical Properties
Fluorescence SWUV: Variable
LWUV: Variable
Irradiated Characteristic Physical properties
Inclusions Diamonds can have naturals, naturals with trigons, bruted girdle surface if not faceted, bearding, sharp facet junctions, angular mineral inclusions, olivine, garnet, diopside, graphite mineral inclusions, parallel growth marks, color zoning, internal grainingRed irradiated diamonds will have an even distribution of color but might show color zoning associated with the facets. In blue stones the color is usually even but can be uneven with blue and colorless zones. Might show facet-related color zoning or color at the culet. Green stones show distinct color zone around the culet in a "umbella" pattern and color zoning that follows the facet junctions.
Stability Good

Fracture-Filled

Fracture filling is the filling of surface-breaking cavities or fissures with highly refractive colorless glass. This process improves the apparent clarity of a diamond.

Fracture-Filled Diamond
Fracture-Filled Classification
Common Name Fracture-Filled
Fracture-Filled Optical Properties
Fluorescence SWUV: Variable
LWUV: Colorless: Variable
Fracture-Filled Characteristic Physical properties
Inclusions Fracture-filled diamonds typically display flash effect or interference color flash in darkfield lighting. Inclusions in these stones are typically trapped gas bubbles, cloudy or discolored material in fractures, crackled or web-like texture. Stone will have drill holes that do not end at a bleached inclusion and there might be evidence of fillers.
Stability Very Good
Tim Matthews

Author

Tim Matthews

Tim Matthews is President and Chief Executive Officer of Jewelry Television® (JTV), as well as a member of the company's Board of Directors. He oversees and leads all aspects of the company's powerful omni-digital retail platform that uniquely specializes in fine jewelry and gemstones. His passion for business and gemstones has led him to become a recognized expert in the field of gemology. He is a life member of the Gemmological Association of Great Britain (Gem-A) and has earned Gem-A's highest degrees, the Gemmology (FGA) and Diamond (DGA) diplomas. He is also a Graduate Gemologist (GG) of the Gemological Institute of America (GIA) and has also completed GIA's Graduate Diplomas in Diamonds, Colored Stones and Pearls. Under his leadership, JTV has become the leader in the sourcing and selling of color gemstones and jewelry.

This page was created on June 27, 2014.

This page was last edited on October 24, 2019.