Examples from the Web for sardonyx
Then there was a pause, and then, last of all, arrived Mr. Sardonyx.
The sardonyx was supposed by the ancients to be a different stone from the onyx.
Mr. Sardonyx bowed and took his hat and his departure at once.
He had a most rich George in a sardonyx set with diamonds of very great value; for the rest, very plain.The Diary of John Evelyn, Volume II (of 2)|John Evelyn
It is a sardonyx of five layers of irregular shape, like all classical gems, measuring 12 in.