Goldsmith
Compared to other metals, gold is malleable, ductile, rare, and it is the only solid metallic element with a yellow color. It may easily be melted, fused, and cast without the problems of oxides and gas that are problematic with other metals such as bronzes, for example. It is fairly easy to "pressure weld", wherein similarly to clay two small pieces may be pounded together to make one larger piece. Gold is classified as a noble metal—because it does not react with most elements. It usually is found in its native form, lasting indefinitely without oxidization and tarnishing.
Diamond simulant
The Mohs scale of mineral hardness is a non-linear scale of common minerals' resistances to scratching. Diamond is at the top of this scale (hardness 10), as it is one of the hardest naturally occurring materials known. (Some artificial substances, such as aggregated diamond nanorods, are harder.) Since a diamond is unlikely to encounter substances that can scratch it, other than another diamond, diamond gemstones are typically free of scratches. Diamond's hardness also is visually evident (under the microscope or loupe) by its highly lustrous facets (described as "adamantine") which are perfectly flat, and by its crisp, sharp facet edges. For a diamond simulant to be effective, it must be very hard relative to most gems. Most simulants fall far short of diamond's hardness, so they can be separated from diamond by their external flaws and poor polish.