Amethyst color chart: shades, names and which color is finest
By HeyGema™ · Updated
In short
Amethyst is purple quartz, from light lilac to deep, intense royal purple. Amethyst often shows color zoning, with angular darker and lighter zones, so look at a stone from several angles before you compare it with another. A round 1 carat amethyst measures about 7.1 mm.
- 3shades on the chart
- 7.1 mm1 carat, round
- 7hardness (Mohs)
Amethyst colors
Amethyst is purple quartz, from light lilac to deep, intense royal purple.
- Deep royal purpleDark and strong.
- Medium purpleA typical stone.
- Light lilacA pale stone.
The swatches are illustrations picked to match the color names. Screens and light change how color looks, and a cut stone changes with the light, so judge a stone in person or from a daylight photo.
Which amethyst color is finest
Amethyst often shows color zoning, with angular darker and lighter zones, so look at a stone from several angles before you compare it with another.
How gemologists describe color
Gemologists describe the color of a stone with hue, tone and saturation, and look at the three together. For colored stones they also look at how evenly the color is spread.
- Hue
- The color you would name, such as blue, green or red, or a blend such as bluish green.
- Tone
- How light or dark that color looks, from pale to very dark.
- Saturation
- How strong or pure the color looks, from dull (grayish or brownish) to vivid.
- Evenness
- How evenly the color is spread through the stone. Color zoning is uneven color, such as bands or patches you can see.
Colored stones have no single color scale like the D to Z scale for diamonds, so sellers use their own words. Ask for a daylight photo and for the size in mm as well as the carat weight.
What affects amethyst color
- Cause of color
- An iron-related color center in quartz, together with natural gamma irradiation. How much iron the quartz holds sets how strong the color can get.
- Treatments
- Heat is the most common treatment. Heating can turn amethyst into green quartz (prasiolite) or into citrine. Heat treatment is nearly impossible to identify, so disclosure rests on the seller.
- Wear and care
- Amethyst is quartz, so it is hard enough for everyday wear.
Amethyst color and size
Carat is weight, not size. A round 1 carat amethyst measures about 7.1 mm, against 6.5 mm for a diamond of the same weight. This table gives the face-up size of a well-cut amethyst.
- 1 ct
- Round: 7.1 mm
- Oval: 8.8 x 6.0 mm
- Cushion: 6.2 x 6.2 mm
- 2 ct
- Round: 8.9 mm
- Oval: 11.1 x 7.6 mm
- Cushion: 7.8 x 7.8 mm
- 3 ct
- Round: 10.2 mm
- Oval: 12.7 x 8.7 mm
- Cushion: 8.9 x 8.9 mm
- 5 ct
- Round: 12.1 mm
- Oval: 15.0 x 10.3 mm
- Cushion: 10.5 x 10.5 mm
- 10 ct
- Round: 15.3 mm
- Oval: 18.9 x 13.0 mm
- Cushion: 13.3 x 13.3 mm
- 20 ct
- Round: 19.2 mm
- Oval: 23.9 x 16.4 mm
- Cushion: 16.7 x 16.7 mm
See the full amethyst size chart for every shape, or use the carat to mm calculator for any weight.
Amethyst properties
- Hardness (Mohs)
- Value: 7
- Refractive index
- Value: 1.544 to 1.553
- Specific gravity
- Value: 2.65
A purple quartz. Light, so it faces up much bigger than a diamond of the same weight.
How to compare amethyst stones
- Look at each stone in daylight and under indoor light. Color shifts with the light.
- Ask for the size in mm as well as the carat weight. A amethyst of the same weight can differ in size by shape and cut.
- Ask whether the color is natural or treated, and ask for the answer in writing.
- For a stone that matters, ask for an independent lab report.
Designing with a colored stone? HeyGema lets you choose the stone shade and renders your design with it.