Where the Old Miner Cut was an antecedent of the modern round brilliant, the Old European Cut was the direct forefather to the modern round brilliant. It was the Old European Cut that was studied for the development of the proportions that would allow the creation of the measurements for the ideal cut diamond. Rounder in shape than the Old Miner Cut, and cut with a circular girdle, the Old European Cut is similar to, but still far from its direct descendent, the round brilliant.

Like the Old Miner Cut, the Old European cut is a rounded, hand faceted cut of diamond. The Old European, as with its direct descendent, the round brilliant, is cut with 58 facets in an effort to maximize brilliance and fire. However, it was developed before the perfection of the diamond saw, and so was primarily hand faceted. This lead to the Old European Cut being cut and polished with a small table, high crown, deep pavilion and an open culet. The deep, faceted pavilion and small table in the Old European cut is designed to bring light in, and reflect its inner fire of color back to the viewer's eye when looking down upon the table.

It is important to note that candlelight and gaslight were the main sources of lighting for gemstones prior to the early 20th century. Each of these is much dimmer, and far more forgiving of flaws, than modern electric lighting. Under the softer lighting of the 19^th century the hand faceting, deep pavilion, open culet and small table resulted in a scintillation that had been unseen in diamonds until then.

This type of faceting, along with the open culet, is effective under candlelight, but under electric lighting, the culet often creates the image of a hole in the bottom of the diamond. However, it is also due to this type of shape that the Old European Cut, like the Old Miner Cut, is better able to hide their actual color. The less than exact nature of the hand faceting, along with the deeper cut and smaller table, provide less light dispersion, and so the diamond can appear lighter in color than it actually is.

While the Old European Cut demonstrates greater attention to the effect of light dispersion on the diamond, it was nevertheless cut for maximum carat weight retention. This is to say that the diamond was still cut and polished in accord with the shape of the rough diamond. Regardless of the Old European Cut's lapse in popularity, the current proportions for the ideal cut of diamond owe a debt to the timeless charm of the Old European cut. It was this diamond shape that Marcel Tolkowsky and Henry Morse, among others, used in experimentation for developing the angle and facet parameters for the ideal cut diamond. Due to the hand-faceting nature of this cut, there are no ideal measurements.