The available image from the 四庫全書 edition (https://ctext.org/library.pl?if=en&file=5647&page=8) is even less clear. However, biographies for these two brothers are given in 南齊書 (https://zh.wikisource.org/wiki/%E5%8D%97%E9%BD%8A%E6%9B%B8/%E5%8D%B739), where their names are written as 劉瓛 and 劉璡. In the cited text the jade radical is changed to the stone radical, so it is clear that the character in question must be ⿰石獻.

▲ 白氏六帖事類集（北宋刊本）卷6 folio 28b


▲ 唐宋白孔六帖（南宋刊本）卷19 folio 3b