Hard sign with grave
Hard sign with grave (Ъ̀ ъ̀; italics: Ъ̀ ъ̀) is a letter that can be used in Bulgarian. It denotes a stressed Ъ. For example, it can be used in the word ъ̀гъл, meaning 'corner' and въ̀лна 'wool, wave'. Computing codes
Being a relatively recent letter, not present in any legacy 8-bit Cyrillic encoding, the letter Ъ̀ is not represented directly by a precomposed character in Unicode either, it has to be composed as Ъ+◌̀ (U+0300). References

Unencoded Cyrillic letters