The symbol representing the four Diamonds together (and thus Homeworld) is found on the 'V' key. To get each Diamond individually, use lowercase 'v', less than (<), greater than (>), and carat (^). I believe capital 'O' is the glyph for 'sun' or 'star', and lowercase 'o' represents 'planet' or 'moon'. That's all I got. Let me know if you have any theories!
Gem Glyph Font
A downloadable font
Though these glyphs haven't yet been entirely deciphered, and though our alphabet isn't exactly a perfect match for them, this Gem Glyph font does appear to bear a similarity to glyphs that may have been seen in SU. This font is not meant to be an exact duplicate, nor does it contain every glyph seen on screen, but it's a fairly reasonable facsimile.
(OTF is compatible with Windows, Mac, and Linux. Built using Glyphr Studio Online)
Install this OpenType Font like you would install any TTF font. You may have to restart some programs to refresh the font cache after installing.