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What is MM size of 18.90 carat Cushion Diamond ?

Diamond (18.90 Carat )

15.52 x 15.52 mm

Stone Type : Diamond
Stone Shape : Cushion
Stone Weight : 18.90 carat
Length X Width : 15.52 x 15.52 mm
Length / Width Ratio : 1.00
Approx Face-up Area : 216.78 mm²
Approx Volume : 1,073.86 mm³

How to Calculate Depth for Cushion Diamond ?

Depth percentage of Cushion cut is the ratio of the total depth (measured from table to culet) to its width.
Recommended Depth percentage range for Cushion Diamond should be between 59% and 70% , Diamonds that fall out of this range are generally less desirable and usually best to be avoided.

Depth = (average diameter × Depth) ÷ 100
Depth(%) = (total depth ÷ average diameter) × 100

Depth percentage is one of the most important measurements as it plays a critical role in diamond's brilliance and appearance. If a diamond is cut too deep or too shallow, light leaks out, making the stone less brilliant and fiery. Deep cuts also add hidden weight.

How many Colors Available for Diamond ?

White , Light Red , Red , Dark Red , Orangey Red , Light Orange , Orange , Light Brown , Brown , Dark Brown , Light Yellow , Yellow , Light Yellowish Green , Yellowish Green , Dark Yellowish Green , Light Green , Green , Dark Green , Light Bluish Green , Bluish Green , Dark Bluish Green , Light Blue , Blue , Dark Blue , Light Violet , Violet , Dark Violet , Light Purple , Purple , Dark Purple , Light Grey , Grey , Black ,


White Light Red Red Dark Red Orangey Red Light Orange Orange Light Brown Brown Dark Brown Light Yellow Yellow Light Yellowish Green Yellowish Green Dark Yellowish Green Light Green Green Dark Green Light Bluish Green Bluish Green Dark Bluish Green Light Blue Blue Dark Blue Light Violet Violet Dark Violet Light Purple Purple Dark Purple Light Grey Grey Black
Diamond Details...

Diamond is the hardest natural material (nothing can scratch it, but another diamond) and a very attractive and expensive gem. Diamonds can occur in a whole spectrum of colors, although white or colorless are the most popular.

Name of Stone : Diamond
Mineral : Diamond
Shape : Cushion
Chemical Formula : C
Crystal Structure : Isometric
Hardness : 10
Specific Gravity : 3.52
Carat weight : 18.90 carat
Gram weight : 3.780 gm
Ounces weight : 0.1333 ounces
Length : 15.52 mm
Width : 15.52 mm
Length / Width Ratio : 1.00
Average diameter : 15.52 mm
Approx Face-up Area : 216.78 mm²
Approx Volume : 1,073.86 mm³
Refractive Index : 2.417 - 2.419
Cleavage : 1
Luster : Adamantine
Birefringence : None
Wearability : Excellent
Birthstone : Diamond is a birthstone for the month of April
Diamond Guidelines 4Cs and More

Before purchasing a diamond, one should make sure it looks its weight. It's important to understand that carat weight does not equal face-up size.

Two diamonds of exactly the same weight (and shape) can vary quite considerably in face-up size. This depends on the proportions of the cut (e.g., deep cuts will face up smaller)..

Face-up area is a measure of the size of the diamond when viewed from the top view.

It tells you how big the diamond is at the girdle plane. It's important for a diamond to have sufficient face-up size for its carat weight

Diamond prices vary greatly as they depend on the combination of unique characteristics (4Cs - Cut, Color, Clarity, and Carat). For best value, it's important to choose the combination that will reduce the price without having a negative impact on appearance.

You also need to consider some of the following points as well

  • Strong blue fluorescence.
  • Fair or Poor symmetry.
  • Extremely thin or extremely thick girdle.
  • Inclusions visible to the naked eye.
  • Diamond Certification.

Blue fluorescence can have a positive, negative, or zero effect on a diamond. Diamonds in the lower color range (H or lower) can benefit from it, as it can make them look whiter, more colorless. On the other hand, strong fluorescence can cause a stone (especially in the higher color range D-G) to appear hazy or milky under certain light conditions. One of the biggest benefits of fluorescent diamonds is that they generally cost less.

Blue fluorescence can be found in 35% of naturally mined diamonds and it makes the stone glow under UV light. Outside of UV lighting environments, there are no visual differences between fluorescent and non-fluorescent diamonds.

However, there exists a big difference in pricing between these diamonds. In the industry, diamonds with fluorescence are usually traded at a 10-15% discount and can go as high as 25% for higher colored diamonds.

GIA grades fluorescence as None, Faint, Medium, Strong, and Very Strong.

There are Many Laboratory Available which provides certification for Gemstones.

  • GIA - Gemological Institute of America
  • AGS - American Gemological Society
  • HRD - The Hoge Raad voor Diamant
  • IGI - International Gemological Institute
  • EGL - European Gemological Laboratories
  • GSI - Gemological Science International

*Different certification labs give different results

Piecut Diamonds are set of small Diamonds, which are cut & polished with Precised Measurements to look like a Single Solitaire diamond which can save 80% to 85% from Solitaire Single Piece Price.

Shapes of Pie Cut Diamonds.

  • 9 Pcs Emerald
  • 9 Pcs Round
  • 4 Pcs Round
  • 3 Pcs Heart
  • 4 Pcs Oval
  • 4 Pcs Pear
  • 4 Pcs Marquise
  • 5 Pcs Star

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