Question

Can all minerals be gemstones?

Answer 1

No, not really.

Explanation:

Most gems are “minerals that have been chosen for their beauty and durability, then cut and polished for use as human adornment.” This definition covers the vast majority of the stones we regard as gems. I think the key is "beauty" which is somewhat subjective an not really scientific. People who collect minerals are frequently trying to convince buyers that a new mineral is in fact a gemstone and is in fact "beautiful". For example, the mineral

See: https://www.gemsociety.org/article/what-is-a-gem/

For example, Ammolite is a trade name given to a thin iridescent aragonite shell material that is found on two species of extinct ammonite fossils (Placenticeras meeki and Placenticeras intercalare). Other less-frequently used trade names for Ammolite are "Calcenite" and "Korite." It is also known simply as "ammonite shell."! see: http://www.canadianammolite.com/AmmoliteFacts.html