Professional Gemstone Weight & Value Calculator
The most accurate gemstone calculator for estimating carat weight and market value for Emeralds, Sapphires, Opals, and more.
Gemstone Weight & Value Calculator
Calculate carat weight and estimated market value
Enter dimensions and a quality grade, then calculate
Weight uses volume × shape factor × specific gravity. Value uses your selected grade.
Accurate Calculations
Uses precise specific gravity (SG) measurements for scientifically accurate weight estimations.
Market Value Estimates
Get instant price ranges based on current market data and quality grades.
Avoid Overpaying
Make informed purchase decisions with reliable worth and appraisal estimates.
Multiple Shapes
Supports all popular gemstone cuts including round, oval, emerald, pear, and more.
How to Measure Your Gemstone
Measure Dimensions
Use a digital caliper or ruler to measure the length, width, and depth of your gemstone in millimeters. Accuracy is key for precise calculations.
Select Gemstone Type
Choose your gemstone type from the dropdown. Each stone has a unique specific gravity that affects weight calculations.
Choose Grade & Get Results
Select Commercial, Fine, or Extra Fine quality. Weight is volume × shape factor × specific gravity; value uses your grade. Copy results for your records.
Understanding Specific Gravity in Gemstone Calculations
Our gemstone calculator uses the scientific principle of specific gravity (SG) to provide accurate carat weight estimations. Specific gravity is the ratio of a gemstone's density compared to water, and each gemstone type has its unique SG value.
Why Specific Gravity Matters
Two gemstones with identical dimensions can have vastly different weights. For example, a 10mm sapphire (SG: 4.0) weighs significantly more than a 10mm emerald (SG: 2.72). Our calculator accounts for these differences to give you precise estimates.
Professional-Grade Accuracy
Used by jewelers and gemologists worldwide, this tool helps you determine the approximate price, value, worth, and appraisal range of your gemstones before making purchase or sale decisions.