The history of diamond cuts in Europe can be traced to the late Middle Ages, before which time diamonds were employed in their natural octahedral state—anhedral (poorly formed) diamonds simply were not used in jewelry. The first "improvements" on nature's design involved a simple polishing of the octahedral crystal faces to create even and unblemished facets, or to fashion the desired octahedral shape out of an otherwise unappealing piece of rough. This was called the "point cut" and dates from the mid 14th century; by 1375 there was a guild of diamond polishers at Nürnberg. By the mid 15th century, the point cut began to be improved upon: the top of the octahedron would be polished or ground off, creating the "table cut". The importance of a culet was also realised, and some table-cut stones may possess one. The addition of four corner facets created the "old single cut" (or old eight cut). Neither of these early cuts would reveal what diamond is prized for today; its strong dispersion or "fire". At the time, diamond was valued chiefly for its adamantine lustre and superlative hardness; a table-cut diamond would appear black to the eye, as they do in paintings of the era. For this reason, colored gemstones such as ruby and sapphire were far more popular in jewelry of the era.