How many letters does the top answer for “a deep orange-red variety of chalcedony” have?

The most common answer is sard (4 letters).

Crossword clue: a deep orange-red variety of chalcedony

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

sard 4 letters wn-def

a deep orange-red variety of chalcedony

sardius 7 letters wn-def

a deep orange-red variety of chalcedony

a translucent red or orange variety of chalcedony 67% similar → carnelian, cornelian