Not being anything other than white I have no idea how someone who isn't white would describe themselves in remote communications. However I am more than willing to amend my post to keep in line with the modern woke society.
If you can let me know what less than white gentlemen call themselves in such situations I will do so immediately. 
Edit.
As age is a protected characteristic under the discrimination legislation I should add that I find the comment "Maybe quite relevant to the conversation about age lol." to be as, if not more offensive than anything I have inadvertently posted.
I think typically in your example most punters would just introduce themselves and state their actual race/ethnicity.
A black man would say 'I'm a black guy, is that alright?'
A south asian man would say 'I'm a south asian guy, is that alright?'
An east asian man would say 'I'm an east asian guy, is that alright?'
I don't think anyone would describe themselves as 'coloured'.
I wasn't having a dig at your age or suggesting that being older is anything bad. I mentioned it because although 'coloured' is now very outdated and considered racist, it was commonplace terminology in the UK decades ago, so I suspect you used it without intending to cause offence, as i mentioned in the post.
Welcome to the woke brigade
