There are more words but they are from Tolkien's earlier conceptional periods. Tolkien likely changed these words as he evolved the aesthetics and completeness of the languages. You may even find languages that Tolkien later rejected. Do not mix words from different time periods unless you are familiar with the phonetic developments.
glass
noun. brilliance, clarity
glâs
noun. brilliance, clarity
celeg Archaic
noun. glass
talp
noun. glass
celchin
adjective. of glass
libli
noun. small glass; small drop
A word in the Gnomish Lexicon of the 1910s meaning either “a small glass” or “a small drop” (GL/54), based on the early root ᴱ√LIPI as suggested by Christopher Tolkien (QL/86; LT1A/limpë).
celc
noun. glass, a glass
celegrin
adjective. glassy, like glass
crithosceleg
proper name. Disc of Glass
Below: Tolkien's Late Period (1950–1973). These are from Tolkien's late conceptual period — his most settled forms of the languages. Prefer these over the earlier ones above when composing new text.
The Gnomish Lexicon of the 1910s had several glass-related adjectives: G. {celcin} > celchin “of glass”, G. {celcwed} > celchwed “glassy”, and G. celegrin (archaic cailegrin) “glassy, like glass”, all based on the nouns G. celc or celeg/caileg “glass” (GL/25).
Neo-Sindarin: For purposes of Neo-Sindarin I would update these to an adjective ᴺS. heledhren “glassy, like glass, of glass” based on the later Sindarin word heledh for “glass”.