In the US, people generally graduate high school when they are 18 (In Britain, 11th year is the equivalent to 10th grade here and we don't have sixth form college like Britain). Then, if you choose to go on to college (same as 'university'), its 4 years (in most cases) to get an undergraduate degree. 2 more years to get a masters degree, another 2 years to get a doctorate. So, I'm in the 3rd year of getting my undergraduate degree.
I was assuming your British, am I right?
We use the term diploma for the certificate you receive when you complete high school or additional higher education.
ps. Its actually phosphate, but the structure is almost identical to permanganate, so I guess it could be either