Dwarvish is written using square-based glyphs which are the same as the sixteen Dwarvish numerals, rotated one-eighth of a turn to the left. It’s written right to left.

There are eight “stoppers”, sounds which can’t be extended in time without repeating them: K, Ch, T, P, G, J, D, B.
There are eight “sliders”: R, F, S, M, L, V, Z, N.
Written with a central dot, the sounds are softened or made breathy. The breathy versions of S and Z are Sh and Zh, the others just sound breathier.

See Dwarvish Language.

Human languages are written in the Dwarvish alphabet for day-to-day use, modified with vowel markers since Dwarvish doesn’t use vowels. The vowel markers are simply tiny diamond-shaped marks, made with the pen tip, at one or more of five heights on the side of the square they precede or follow. If two vowel marks are shown, the vowel is a diphthong, though these are uncommon in most human languages.

Elvish script is rounded, beautiful, and used for high-culture purposes such as literature, social invitations among the Gold Class, and calligraphed Oath Records. Elvish, in contrast to Dwarvish, is full of vowels.

In the Pektal-speaking lands, at least, there’s a convention about ink colours, as follows:

Blue is for commercial correspondence.
Black is for official purposes.
Red is between lovers and friends.
Purple is within the family.
Green is for education and between academics. (The Master-Mage’s letter to Hope would have been in green ink.)
Brown is for religious correspondence.

Books are printed in black ink for readability, however.