Hi Christopher!
You should have a lot of fun looking around here. Click that red 'glossary' link up at the top of the page - that will answer most of your questions, including what bulino is.
The colors you see on engraved items are usually inlays of other metals. Silver and gold (in various colors) are the usual choices. Normally the metal you inlay has to be softer than the metal you're putting it in to, but you
can put a harder metal into a softer one by sort of reversing parts of the process.
Read through the Tutorials section - that will also give you a good start.