According to Mathur "the modern fountain pen nib may be traced back to the original gold nib which had a tiny fragment of ruby attached to form the wear-point". Nibs tipped with platinum group alloys such as iridium have been used since the 1830s. Today, the main part of the nib are usually made of stainless steel and/or gold The most popular gold content is 14 carat (58⅓%) and 18 carat (75%). The idea is that the nib should be flexible yet firm, and the tip extremely hard-wearing.