Jewel・Summer “Kougyoku” – Japanese Kanji Symbols for Ruby 投稿者: japanese-kanjisymbols 投稿日: 2011/07/042011/06/30 I wrote “Kougyoku“. It’s Japanese kanji symbols for “Ruby”. It’s one of the birthstones of July. “Kou” means Crimson “Gyoku” means Jewel As for the stone words, Ardor, Passion, Innocent love. What jewel Do you like? Please let me know your favorite words about a jewel.