Ok , have started reading about titanium wire mainly from ecf and yes, you can expect grade 1 titanium, when heated, to form blue colour and some golden dots as as i mentioned - basically u can get rainbow colours. Its the oxide forming. And this oxide wont come off easily so its perfectly safe. IF you heat it quite a lot ( dry burn ) , then it might start turning grey. The purer the Ti, the more you have to heat it for it to turn grey.
In fact, it seems like if you get a white coating which comes off easily, you probably have impure titanium - will confirm as i read more and get a better understanding.
Also, you should make a coil and check its resistance, if its showing the expected value ( from steam-engine ). That will also give a first idea if your titanium is pure.