Emerald is a precious gemstone and a variety of the mineral beryl colored green by trace amounts of chromium and sometimes vanadium. Beryl has a hardness of 7.5–8 on the Mohs scale. Most emeralds are highly included, so their toughness is classified as generally poor. Emerald is a cyclosilicate.

Opal is a hydrated amorphous form of silica; its water content may range from 3 to 21% by weight, but is usually between 6 and 10%. Because of its amorphous character, it is classed as a mineraloid, unlike crystalline forms of silica, which are classed as minerals.

A pearl is a hard glistening object produced within the soft tissue of a living shelled mollusk or another animal, such as a conulariid. Just like the shell of a mollusk, a pearl is composed of calcium carbonate in minute crystalline form, which has been deposited in concentric layers.

Ruby is a dynamic, interpreted, reflective, object-oriented, general-purpose programming language. It was designed and developed in the mid-1990s by Yukihiro "Matz" Matsumoto in Japan. According to the creator, Ruby was influenced by Perl, Smalltalk, Eiffel, Ada, and Lisp.

Topaz is a silicate mineral of aluminium and fluorine with the chemical formula Al₂SiO₄(F, OH)₂. Topaz crystallizes in the orthorhombic system, and its crystals are mostly prismatic terminated by pyramidal and other faces

Turquoise is an opaque, blue-to-green mineral.It is rare and valuable in finer grades and has been prized as a gemstone and ornamental stone for thousands of years owing to its unique hue.