Code point
U+233A
Glyph appearance depends on your fonts.
U+233A
SoU+233A APL FUNCTIONAL SYMBOL QUAD DIAMOND is a Unicode 16.0.0 character in the Other Symbol category. It belongs to the Miscellaneous Technical block.
Choose the representation you need, then copy its value.
U+233A
9018
⌺
⌺
E2 8C BA
233A
0000233A
%E2%8C%BA
\u233A
\u233A
\u233A
\233A