Antique diamond knowledge
Old mine cushions return light in broader, slower flashes than many modern brilliants. Their high crowns, small tables, open culets and individual proportions create the effect. Judge the pattern in motion and under several lights, using photographs alongside video.
“Sparkle” is doing too much work
Three effects deserve separate names. Brightness is reflected white light. Fire is white light split into spectral colour. Scintillation is the changing pattern of flashes and contrast seen when the diamond, viewer or light moves.
A diamond reflects its surroundings as well as the light source. Change the room, distance or angle and the pattern changes. A still image records one angle and lighting setup. Movement reveals how the pattern changes.
Why an old mine cushion looks different
Old mine cuts commonly have a softly squared outline, small table, high crown, visible culet and short lower-half facets. Historical examples vary because cutters followed the crystal and worked by hand.
The broad facets often read as distinct events: one large flash appears, fades and hands the light to another part of the stone. The culet may appear as a central point, then recede as the diamond tilts. A modern round brilliant uses a more standardised optical pattern. Compare their patterns to find the rhythm you prefer.
The museum identifies the brooch by date, materials and place. Its varied stone outlines show how different shapes can work together. A centre stone belongs to a composition: setting, side stones, scale and normal viewing distance all affect the result.
Broad facets change the pace
Dealers use “slower” to describe large facets switching on and off over a broader arc of movement. A good antique cushion feels rhythmic. A weak one may hold a large dark area or lose life at normal distance.
Motion separates contrast from darkness
The rotating view below shows an actual 3.06 ct G VVS2 old mine cushion brilliant. Watch the culet, then the broad reflections around it, then the smaller perimeter facets.
Healthy contrast moves. A dark area caused by the camera or viewer should change as the stone tilts. A fixed dark region that survives different angles, distances and lights deserves closer study. Video still has limits: exposure, compression and screen brightness can change colour and intensity.
Use three kinds of light
- Diffuse light: check the spread of white brightness and any persistent dark areas.
- Small direct lights: look for fire and the size of individual flashes.
- Ordinary room light: judge how the diamond behaves where it will be worn.
Include the room lighting in which you expect to wear the diamond.
Combine the report with the moving view
A grading report records measurements, weight, colour, clarity and other characteristics. Photographs, profile views and video add detail about the outline, weight distribution and movement of an antique cushion. Two stones with similar grades can look unrelated.
That is why our diamond dossiers combine laboratory information with photography and video when available.
A practical viewing sequence
- Read the outline at normal distance.
- Watch one slow rotation without pausing.
- Repeat while tracking the culet and broad facets.
- Change the light and camera distance.
- Use magnification for condition, then return to the naked-eye view.
Compare the compact pattern of this 3.01 ct G VS2 old mine cushion brilliant with the more spacious face-up pattern of this 8.01 ct H VVS2 old mine cushion. Follow how the corner shapes and facet sizes change the pattern.
For current availability, reports or a private presentation in several lighting conditions, contact Imperial Cushions.