onyx; banded agate
Mineralogy term for a variety of chalcedony with parallel bands, often used in jewelry and decorative objects.
This ring uses onyx.
Onyx is a gemstone characterized by parallel banding.
オニキス is the common loanword for onyx, often used in fashion and jewelry contexts, while 縞瑪瑙 is the native mineralogical term.
Compound of 縞 (shima, 'stripe') and 瑪瑙 (menō, 'agate'), literally 'striped agate'. The reading is the standard kun'yomi for 縞 and on'yomi for 瑪瑙.