Gem Carat Weight Calc

Not Reviewed
Calculator / Last modified by KurtHeckman on 2016/10/26 06:03
Round Faceted Emerald Cut Faceted
Pear or Teardrop Long Rectangular Cut
Cabochon Cut Navette or Boat-shaped
Cushion Faceted Square Cut Faceted
Heart Shape Faceted Marquise Faceted
Specific Gravity Oval Faceted

The Carat Weight of a Gem Calculator accurately estimates the carat weight of a gem based on is shape (see diagram), dimensions and the type of gem (e.g. ruby).  The type of gem is used to look up the specific gravity of the gem which is combined with the approximate volumetric size to compute the carat weight.  AllCuts.png common gem cuts  

Instructions

First, choose the gem shape / cut (see diagram).  Then, select gem type (see table).  Finally, enter the gem's dimension.  The calculator will then provide an accurate estimate of the gem's carat weight.  The following shapes and cuts are supported:

  • Round Faceted: This computes the Carat Weight of a Round Faceted Gem base on the gem type (e.g. emerald) and the dimension.
  • Pear or Teardrop This computes the Carat Weight of a Pear or Teardrop shaped gem based on the gem type (e.g. Agate) and the dimensions.
  • CabochonThis computes the Carat Weight of a Cabochon cut Gem based on the gem type (e.g. Alexandrite) and the cut dimensions:
  • Cushion Faceted: This computes the Carat Weight of a Cushion Faceted cut Gem based on the gem type (e.g. Amethyst) and the cut dimensions.
  • Heart Shaped FacetedThis computes the Carat Weight of a Heart Shaped Faceted cut Gem based on the gem type (e.g. Andalusite) and the cut dimensions.
  • Emerald Cut FacetedThis computes the Carat Weight of an Emerald Cut Faceted Gem based on the gem type (e.g. Aquamarine) and the cut dimensions.
  • Long Rectangular: This computes the Carat Weight of a Long Rectangular cut Gem based on the gem type (e.g. Blue Topaz) and the cut dimensions.
  • Navette or Boat-shaped: This computes the Carat Weight of a Navette or Boat-shaped Gem based on the gem type (e.g. Cats Eye) and the cut dimensions.
  • Square Cut FacetedThis computes the Carat Weight of a Square Cut Faceted Gem based on the gem type (e.g. Onyx) and the cut dimensions.
  • Marquise FacetedThis computes the Carat Weight of a Marquise Faceted Gem based on the gem type (e.g. Precious Topaz) and the cut dimensions.
  • Oval FacetedThis computes the Carat Weight of an Oval Faceted Gem based on the gem type (e.g. Sapphire) and the cut dimensions.
  • Specific GravityThis returns the Specific Gravity of any Gem based on the type of gem (e.g. Tanzanite).

Description

                 SUPPORTED TYPES OF GEMS
 Agate  Alexandrite Almandite garnetAmethyst
Aquamarine Beryl  Bloodstone  Blue topaz
Carnelian Cats eyeChalcedonyChrysoberyl
CitrineCorundumDemantoid garnetDiamond 
Emerald Golden beryl Green beryl Kunzite
Lapis lazuliMorganiteOnyx Opal 
Precious topazPyrope garnet Quartz  Rose Quartz
 RubySapphireSardonyx  Smokey quartz 
Spessartite garnetTanzanite (zoisite) TopazTourmaline 
 Tsavorite garnet Turquoise Yellow topaz Zircon
SPECIFIC GRAVITY
 GEM SHAPES
* Round (circular) Faceted
* Pear or Teardrop shaped
* Cabochon
* Cushion Faceted
* Heart Shaped
* Emerald Cut
* Long Rectangular
* Navette or Boat shaped
* Square Cut Faceted
* Marquis Faceted
* Oval Faceted
DIAMOND CUTS

The Carat Weight Calculator  has equations and data useful for Jewelers and other merchants of gems.  The equations for gems (including diamonds) provide the approximate carat weight of a gem based on its shape and dimensions.  These equations approximate the volume of the gem and use the specific gravity to provide a karat weight estimate.  The different weight approximations are based on the shape of the gem (see list of cuts below). 

The gem cuts include:round (circular), oval, emerald cut, long rectangular, square, navette or boat-shaped, pear-shaped or teardrop, cabochon, princess cut, Cushion cut, Old European cut.

NOTE: Never use an estimating equation for the weight of a gem if you can weigh it on a quality jeweler's scale.  These equations are useful when the jeweler is trying to preserve the setting of the gem while still providing a carat weight estimate.  In this way, the jeweler can ascertain the type of gem, its shape and then using precise measuring tools measure the salient dimensions for use in these equations.  These steps can be done while the gem remains in the setting.

The vCalc Jeweler's calculator is free to use like all the other equations and calculators found in vCalc.  Please feel free to comment on this wiki page using the comment button below and help us make a better Jeweler calculator for you.

APPLICATIONS

This calculator provides Jewelers and other merchants of gems and precious metals to compute an estimated current market value for jewelry items.  Likewise private owners and insurance providers can make similar estimates for use in establishing the basis for insurance valuation and coverage.

AUTHORITATIVE SOURCE

The equations and data used in vCalc's jewelry library and calculator were reviewed by a certified gemologist.   The equations are based on industry recognized formulas and data.  The table below shows a comparison of computations between vCalc and an industry accepted application (Quantum Leap).

The length, width and depth are in millimeters (mm), and the Quantum Leap and vCalc measurements are in carats (cwt).

QL-Verif.png

The largest variance, an oval faceted alexandrite, which can be seen in the last row above, has been double checked against several source equations which tend to support vCalc's accuracy.

See Also

  • Jeweler's Calculator - Carat weight estimator for diamonds and other gems, and suite of tools for estimating the value of scrap precious metals.
  • Precious Metals Calculator - Near real-time quotes on the SPOT price of Gold, Platinum, Palladium and Silver, with formulas that calculate buy price based on SPOT price, purity (% or karat), refiner's fee and profit (fee).