A "peripheral blood smear", which is used to look at the appearance of the blood cells under the microscope, would detect the presence of blast cells. There may be other ways to do it too. Your doctor should understand what you are asking for and be able to tell you what test(s) s/he uses to find the answers.
Similarly, I believe the test for ringed sideroblasts is called an "iron stain", which is done on a blood sample. It might also be called a "siderocyte stain". Your doctor should be able to tell you how s/he typically tests for these.
Diagnosed AA 10/96, MDS/RA 6/98, MUD/BMT 10/6/98