DG-M5 Amethyst: Pros, Cons & Light Return

Amethyst is quartz, with a refractive index of about 1.55, the lowest of the gemstones on this site. A pavilion cut for it has little room for error. DG-M5 answers with a single tier of twenty-four pavilion mains, all at 41.49°, about a degree past amethyst's guide minimum of 40.4°.

The 85-facet plan was drawn for moissanite, yet in our census it tops every cut we measure in amethyst for brilliance and comes last for leakage: the clearest win on our amethyst pages.

Two things go the other way. It keeps less of its light when tipped than the diamond version does, and quartz's weak dispersion holds its fire well under the diamond figure.

Is DG-M5 the best round for amethyst? Pros and cons

Pros

A quarter lighter than diamond 0.74 vs 0.98 ct
The most light of any cut we measure here 85 vs 72
Less light out of the back 15 vs 28
A little more sparkle than the T73 85 vs 80

Cons

Holds less light when tipped 63 vs 83
Less fire than the diamond version 50 vs 67

Compared with the T73 Round Brilliant in amethyst and with the DG-M5 in diamond. A difference counts from 3 points (Brilliance, Fire, Tilt, Leakage), 5 (Scintillation, Symmetry), 2 (Spread) or 5% (weight); Tilt counts as a pro only for a stone within 5 points of the brilliance it is compared with. How we measure.

All eight scores against the T73

At a glance: the DG-M5 in amethyst (white) against the T73 Round Brilliant in amethyst (dashed): solid white where it reaches further, hatched where it falls short. Each pro and con is explained, with pictures, below.

Against the T73 Round Brilliant in amethyst: ahead on 5, level on 2, behind on 1.

Global76, the comparison 70, difference +6
Brilliance85, the comparison 72, difference +13
Fire50, the comparison 36, difference +14
Scintillation85, the comparison 80, difference +5
Spread100, the comparison 100, difference 0
Symmetry100, the comparison 100, difference 0
Shape-norm91, the comparison 77, difference +14
Tilt63, the comparison 80, difference −17

Face-up light census, a different measure from the Cut Grading Tool; Spread and Shape-norm above 100 sit on the ring.

Open it in the Cut Performance Wheel

What amethyst gains in DG-M5

A quarter lighter than diamond

0.74 ct at 6.5 mm, against 0.98 ct for the same cut in diamond (−25%)

Quartz has a specific gravity of 2.65 against diamond's 3.52. A DG-M5 6.5 mm across weighs 0.74 ct in amethyst, where the diamond version comes to 0.98 ct.

A DG-M5 6.5 mm across, weighed from the model's measured volume and each stone's specific gravity.

Try it yourself: Weights in all seven gemstones on the DG-M5 page

The most light of any cut we measure here

Brilliance 85 against 72 for the T73 Round Brilliant in amethyst: 13 points higher

Twenty-four pavilion mains instead of eight give light that misses one main another chance at the right angle. DG-Anteros comes next in amethyst at 82; the T73 trails both.

Dg-m5 in amethyst face-up Light Return map: red, green and blue show where the light returns from, grey shows where it leaks (Brilliance 85) — Red, green and blue = light returning to the eye; grey = light leaving through the pavilion. This is the head-on view; the Brilliance score averages a wider cone of light, so the score can differ from what one picture shows.

T73 round brilliant in amethyst face-up Light Return map: red, green and blue show where the light returns from, grey shows where it leaks (Brilliance 72) — Red, green and blue = light returning to the eye; grey = light leaving through the pavilion. This is the head-on view; the Brilliance score averages a wider cone of light, so the score can differ from what one picture shows.

Try it yourself: Open this Light Return map in the simulator

Less light out of the back

Leakage 15 against 28 for the T73 Round Brilliant in amethyst: 13 points lower

Only 15% of the light in our census escapes through the pavilion, the smallest share of any cut we measure in amethyst. The T73 lets out 28% in the same stone.

Dg-m5 in amethyst tilted 0 degrees: Light Return map, 0% of the face leaking — Each frame is the Light Return map with the stone tilted away from you by the angle shown; grey is light leaving through the pavilion. The share under each frame is that picture's own.

Dg-m5 in amethyst tilted 10 degrees: Light Return map, 32% of the face leaking — Each frame is the Light Return map with the stone tilted away from you by the angle shown; grey is light leaving through the pavilion. The share under each frame is that picture's own.

Try it yourself: Tilt it yourself in the simulator's light map

A little more sparkle than the T73

Scintillation 85 against 80 for the T73 Round Brilliant in amethyst: 5 points higher

Our scintillation score follows the facet plan, and 85 facets in a twelve-fold ring give it more to count than the T73's 73.

DG-M5 · 85 facets · Scintillation 85

T73 Round Brilliant · 73 facets · Scintillation 80

Scintillation follows the number of facets: more facets, more and smaller flashes as the stone moves. Count the facets in each crown. Drawn from each cut's own model.

Try it yourself: Compare the Scintillation spoke in the Cut Performance Wheel

Where DG-M5 gives ground in amethyst

Holds less light when tipped

Tilt 63 against 83 for the DG-M5 in diamond: 20 points lower

Tilted by 20°, DG-M5 keeps 63 of its face-up light in amethyst, against 83 for the diamond version. Its strength is straight on; tipped, more light meets the single-angle pavilion too squarely for quartz to hold.

What helps: If the stone will be seen at an angle, as in a drop earring, the T73 Round Brilliant Amethyst keeps 80 when tipped, though it starts from less light: 72 against 85.

Try it yourself: Compare the Tilt spoke in the Cut Performance Wheel

Less fire than the diamond version

Fire 50 against 67 for the DG-M5 in diamond: 17 points lower

Diamond spreads white light into colour more than three times as strongly as quartz, 0.044 against 0.013, and no facet plan makes up that difference. It still out-fires the T73 here, 50 against 36.

Dg-m5 in amethyst face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 50) — Look at the coloured flashes: those are fire. Same light, same size, same face-up angle; rendered by our 3D Gemstone Simulator from each cut's own model.

Dg-m5 in diamond face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 67) — Look at the coloured flashes: those are fire. Same light, same size, same face-up angle; rendered by our 3D Gemstone Simulator from each cut's own model.

What helps: Among rounds, DG-Anteros Amethyst edges ahead at 54. For the most fire we measure in this stone, the Oval Cut Amethyst reaches 69.

Try it yourself: See the fire in the 3D Gemstone Simulator

Who a DG-M5 amethyst suits

For a round amethyst meant to show as much light as quartz allows, this is the cut we would choose: Brilliance 85, leakage 15%, and more sparkle than the T73. It suits a solitaire seen mostly face-up.

Amethyst is a favourite first stone for hobby cutters. DG-M5 asks for one pavilion angle on all twenty-four mains, so the pavilion has a single setting to get right.

If the stone will hang and swing, the T73 Round Brilliant Amethyst holds more of its light at an angle. For coloured flashes over light, the Oval Cut Amethyst.

DG-M5 Amethyst: questions

What is the best round cut for amethyst?

Of the rounds we measure, DG-M5: Brilliance 85, then DG-Anteros at 82 and the T73 at 72.

Does DG-M5 amethyst have fire?

Some: Fire 50 in our census, more than the T73's 36 in amethyst but well under the diamond version's 67.

Why does DG-M5 leak less than the T73 in amethyst?

Our census measures the result, 15% against 28%, not the reason. Its single pavilion tier sits at 41.49°, a little steeper than the T73's 40.75°.

How much does a 6.5 mm DG-M5 amethyst weigh?

About 0.74 ct; cut from diamond, a stone that wide would be 0.98 ct.

Get the DG-M5 Cut files

6 formatsMillimetresWatertight

DG-M5 Cut 3D files

The DG-M5 Cut as exact geometry: 85 planar facets, real-world scale, ready for CAD, rendering, printing and casting.

STEPExact faceted solid for CAD
3DMRhino, closed mesh on its own layer
STLWatertight mesh for printing and casting
OBJMesh for modelling and rendering
FBXBlender, 3ds Max, Maya, Cinema 4D, Unity, Unreal
GLBWeb, AR and quick previews

€9.99 · Personal useBuy the 3D files

GemCad96 index

DG-M5 Cut cutting files

The DG-M5 Cut as a faceting design: 61 + 24 girdles = 85 facets, 96 index, 12-fold mirror-image symmetry, ready for the machine.

.ascGemCad design file, 96 index gear
.csvTier table: angles, indices and cutting order
DiagramPrintable faceting diagram

€9.99 · Personal useBuy the cutting files

Questions before you buy? Email us.

More gemstones and cuts

Amethyst: optical properties and the top ten cuts · The DG-M5: specifications, model and files

DG-M5 Amethyst: more light back than any other cut we measure here