Chatham Created Gems

Size Vs. Weight

Carat is a measurement of weight, not size. Because different gemstones have different densities, one can weigh significantly more than the other for the same physical size. Consider a 3 inch ball of cork vs. a 3 inch ball of lead. Which weighs more? They are both 3 inches in diameter. But the ball of lead weighs much more because lead is denser than cork. Likewise, ruby and sapphire are denser than diamond. A 1 carat round diamond is about 6.5mm, while a 1 carat ruby is only 6mm. So if you order a 1 carat ruby based on the size of a 1 carat diamond, then the ruby will be much smaller than you expect. Likewise, a 6.5mm round emerald weighs .95 ct. A 6.5mm diamond weighs 1 carat and a 6.5mm blue sapphire weighs 1.36 carats.

For this reason, it’s important to always order colored stones based on the physical size you need, rather than the carat weight. Too often people are gauging the size they need based on diamond carat weights, and that simply doesn’t work with colored stones. Please use the chart below to help you determine what size gemstone you need.

Chatham Created Gems

Chatham Loose Stone Size Vs. Weight Chart

Now you can SAVE on Chatham loose stones from JewelryImpressions.com. Refer to the chart below to determine the size and carat weight of stone you’re interested in. Please note, weights and sizes on this chart are estimates and can vary up to 10% either way.  For more detailed information and prices, select the gemstone you want  to the left.

Round (mm)
Diamond (ct.)Emerald (ct.)Ruby & Sapphire (ct.)Alexandrite (ct.)
2.00.030.030.040.04
2.50.060.060.080.08
3.00.100.100.150.14
3.50.160.150.220.19
4.00.220.220.340.33
4.50.330.320.450.43
5.00.450.450.660.59
5.50.590.570.830.75
6.00.770.721.091.05
6.51.000.951.361.23
7.01.251.101.641.63
7.51.551.402.122.00
8.01.851.752.502.35
Oval (mm)
Diamond (ct.)
Emerald (ct.)
Ruby & Sapphire (ct.)
Alexandrite (ct.)
5×30.250.200.290.29
6×40.520.400.590.54
7×50.930.661.061.00
8×61.451.131.651.50
9×72.071.602.362.20
10×83.082.403.503.26
11×94.313.404.904.10
12×105.984.106.805.60
Trillion (mm)
Diamond (ct.)
Emerald (ct.)
Ruby & Sapphire (ct.)
Alexandrite (ct.)
3×30.110.090.120.12
4×40.270.220.320.29
5×50.520.430.650.55
6×60.910.680.950.87
7×71.431.101.601.43
8×81.771.552.001.89
9×93.042.253.423.00
Marquise (mm)
Diamond (ct.)
Emerald (ct.)
Ruby & Sapphire (ct.)
Alexandrite (ct.)
4×20.100.080.120.10
4.5×2.50.130.100.150.14
5×2.50.180.120.200.19
5×30.210.160.240.22
6×30.250.210.290.27
7×3.50.350.320.450.40
8×40.730.500.750.66
9×4.50.900.651.000.95
10×51.000.951.301.22
12×62.001.502.061.90
Octagon (mm)
Diamond (ct.)
Emerald (ct.)
Ruby & Sapphire (ct.)
Alexandrite (ct.)
5×30.250.250.350.33
6×40.500.480.700.65
7×51.000.871.301.20
8×61.761.352.001.86
9×72.702.163.102.86
10×83.903.004.404.18
11×95.504.006.186.00
12×107.405.108.307.90
Pear (mm)
Diamond (ct.)
Emerald (ct.)
Ruby & Sapphire (ct.)
Alexandrite (ct.)
5×30.220.200.250.23
6×40.460.350.530.49
7×50.760.580.870.80
8×50.900.761.020.95
9×61.421.051.621.45
10×72.141.592.432.27
11×93.723.004.183.95
Heart (mm)
Diamond (ct.)
Emerald (ct.)
Ruby & Sapphire (ct.)
Alexandrite (ct.)
3×30.110.090.150.14
4×40.270.220.320.31
5×50.520.430.650.57
6×60.910.681.000.90
7×71.431.101.601.52
8×81.771.552.002.05
9×93.042.253.423.10
Square (mm)
Diamond (ct.)
Emerald (ct.)
Ruby & Sapphire (ct.)
Alexandrite (ct.)
2×20.060.040.060.07
3×30.200.120.220.21
4×40.500.280.560.45
5×50.600.500.800.75
Baguette (mm)
Diamond (ct.)
Emerald (ct.)
Ruby & Sapphire (ct.)
Alexandrite (ct.)
4×20.110.100.140.12
5×30.270.200.320.28
6×40.600.470.660.63
7×51.050.901.201.11
  • Sizes specified are given in millimeter (mm) measurements.
  • All above weights are based on average depth and girdle thickness. Larger stones are subject to a wider weight range. Sizes & weights can vary up to 10% either way.

Chatham Created Gems

Chatham round alexandrite

Alexandrites

Chatham princess cut aqua spinel

Aqua Spinels

Chatham oval blue sapphire

Blue Sapphires

Chatham Champagne Sapphires

Champagne Sapphires

Chatham Octagon emerald

Emeralds

Chatham Trillion Padparadscha

Padparadschas

Chatham Pink Champagne Sapphire

Pink Champagne Sapphires

Chatham cushion cut pink sapphire

Pink Sapphires

Chatham marquise ruby

Rubies

Chatham Oval Yellow Sapphire

Yellow Sapphires

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Our Work In Madagascar

Changing lives for children and their families

We get our hands dirty!

In 2014 Michelle went to Madagascar to learn about the geology and mineralogy of the country. She was excited to visit some of the mining localities she learned about in her studies to be a Graduate Gemologist. However, it wasn't the sparkly colorful gems that caught her eye. Rather, it was the children...the little gems of Madagascar. Michelle founded www.GemsOfMadagascar.org in 2015. She visits Madagascar for about two months each year doing humanitarian projects, including clean water, sanitation, education and hygiene.

Little Gems Of Madagascar

What We Do

Visit GemsOfMadagascar.org for more details.