Often seen in Victorian period jewellery, the Old Mine Cut, a square-ish Diamond with rounded corners has been around since the 1700’s. An early Brilliant-cut, it is considered to have originated at the Diamond mines in Brazil, which became the world’s main supplier when the mines in India began to run out. We love these stones for their unique personality and old fashioned glowy light dispersion, cut as they were before the invention of electricity to glimmer in candlelight.
As said, Old Mine Cuts are characteristically cushion shaped and have a deep pavilion (the measurement between the base and crown of the stone) being cut in sympathy with the natural crystalline shape of the Diamond crystal. They also have a higher crown, which is the bit at the top of the diamond which slopes inward and is faceted, and also has an open culet, which is the bit right at the bottom of the diamond, which manifests itself as a black dot when looked at from directly above.
'Prior to the patenting of the first, steam-driven bruting machine in 1874, Diamond cutters simply took an octahedron--the most common shape for gem Diamonds which consists of two four-sided pyramids attached base-to-base--and manually rounded off the corners to create a cushion-shaped stone. They then faceted the Diamond from what was left, creating what today is known as an old mine cut.' National Jeweller
The righthand image taken from the book published in 1867; 'Diamonds and Precious Stones' by Harry Emanuel shows many examples of the mine cut shape.
The general characteristics are as follows:
- A roughly cushion or octahedral shape, often unsymmetrical
- Large, chunky and often uneven facets
- A distinctive culet (the extra' facet at the base of the stone)
- A small table (the table is the facet at the top of the Diamond)
- A thicker, unpolished girdle (the girdle is the sides of the Diamond)
Main image from Brilliant Earth.