You can try
If AscW(Character) < 128 Then 'English Character
See "Character Set" in the VBA Help. You can also try < 256 which will catch some other latin characters and common symbols.

See also: http://www.unicode.org/charts/

To insert Arabic Characters, use ChrW
X = ChrW(610) & ChrW(611) & Chrw(612)
I mean no insult, I do not know what the Arabic Characters represented by those three random numbers mean.