Diacritic Variations in Polytonic Greek

A poster in the Apple forums recently asked how he could get a particular form of the circumflex/perispomoni accent to appear in his ancient Greek text.  There are namely two common variations, one looks like a tilde and one like an inverted breve, and he needed the latter.

It turns out that the form of this diacritic for Greek depends on the font.  Of those which cover this range that come with OS X 10.7, Arial Unicode, Geneva, Helvetica, and Times have the inverted breve form, while the rest (Arial, Courier New, Helvetica Neue, Lucida Grande, Menlo, Microsoft Sans, Palatino, Tahoma, Times New Roman) use the tilde.

For some more info, see Section 1.2 of

http://www.tlg.uci.edu/~opoudjis/unicode/gkdiacritics.html