Hard as stone, resists the saw very well when you cut it, and because it is dense and fine-grained, it polishes well. Made an inlay for my Kremona classical guitar, looks good because the bone's beige tone matches the light brown cedar pretty well. Sound is as good as usual with bone. The original inlay on my Kremona sounded good, by the way, and was extremely rigid for a synthetic material, but rather brittle.
I sculpt a sloped inlay for general intonation, then I make very small, very shallow grooves with a miniature round file under the strings that sound too harsh, to lower them a bit until the attack is both punchy and woody. Depending on how you angle the file you can make the string a little longer on the inlay to perfect intonation.
The bone exsudes oil when you handle it (makes it easier to polish), but the oil will evaporate and leave the bone dry with a more sparkly attack.