is listed in LR:385 s.v. SIL as the cognate of Quenya silma of this meaning, but silef is there asterisked, apparently to indicate that it only appears as part of the word Silevril ”Silmaril”. The word silef may also be used = Quenya silima (noun), the crystal substance of the Silmarils.
Sindarin
cal-
verb. to shine
glóren
shining with golden light
silef
shining white
síla
shine white
(i híla, i sílar) Adj.
(glórin-) (golden), lenited ’lóren; pl. glórin.