Only natural diamonds are used in the production of the SPI Supplies brand diamond scribes. Each diamond is cut and shaped to the desired profile, then polished with the fine diamond paste to a mirror finish. The exact hardness of the diamond is anisotropic, meaning that from a crystallographic standpoint, the hardness varies by unit call dimensions. The effective hardness of a particular diamond scribe depends on the crystallographic relationship of the diamond relative to the writing direction. Each crystal set with the plane associated with the highest hardness in the right direction. Care must be taken to ensure that the correct orientation is the one used for the writing tip. If attention is not made to the orientation (lower cost makers of diamond scribing tools don't track the orientation) there will be a differences of hardness from tool to tool, some having harder faces, some having softer faces. This could result in a substantial population of a new batch of diamond scribes useful lifetime. When the SPI Supplies diamond scribes are manufactured, great care is taken to ensure that the right orientation of the diamond is used in order to ensure the longest possible lifetime.
Another important consideration is the degree of polish given to the diamond. The diamond in the SPI diamond scribes are polished to a mirror finish and is imperative for the perfect scribing tool. Some lower cost scribing tools are rough diamonds and not polished at all. Cheaper scribes results in higher friction and less smooth scribed lines which can, result in breaking of the silicon, glass, quartz or other substrate materials. An unpolished diamond scribe can also results in more particulates being generated then on average.
For more precise scribing of your samples, SPI Supplies offers a line of cleaving and scribing tools.