Proper way of refering to yourself, according to graduate level
According to proper etiquette you may use Master as a title (as in “Master Segovia”) if and only if you are:


the heir apparent of a Scottish viscount or baron
a boy not old enough to be called “Mr.”


The New Oxford American Dictionary (which gives the above information) also lists the archaic use as a  “title for a man of high rank or learning”, but (a) that is archaic, (b) it was not linked to a specific degree, just a courtesy title.

There is no formal title in British English or American English to designate someone who holds a Master's degree. Get over it, and earn a PhD! :)