You've sung about the challenges facing young black men in America. As a mother, how did you react to the Trayvon Martin case?
Oh, I didn't do well with it at all. I have a son, so it just changed everything, those few days. Even at 16 or 15 or 14, they're still our babies. They're still young, they're still very impressionable and they've got to find their way, yet can be so misunderstood. As a mum, I couldn't imagine my son having to come up against that kind of stuff: being killed because of something so simple.
Did it affect your view of the US?
We've lived through a lot – the march and Martin Luther King and so many other things. Even though we've had change to some degree, we still look for things to be a lot different to how they are. It reminds us we still have so far to go.
You've said that you felt some people misinterpreted the message of Rich Girl, your last studio album...
Rich Girl, from a spiritual point of view, for me is about being rich in life, rich in love, rich in all the things that come for free. Everything else that comes with a price, you've got to work for. But the richest things are things you're born with – and those are the things that I live for.
What do you make of all the Nike and Coke tie-ins that mark a lot of modern hip-hop?
Consumerist messages and all of the endorsements are great for the artists themselves. But if we get so consumed with just that, and don't get beyond it, then the only people who are benefiting are the creatives of Pepsi, the creatives of Coke, the creatives of all these things that we're trying to sell.
You've posted a YouTube tribute to Gladys Knight and people on Twitter are calling for you to play her in a biopic. Is she a big hero?
When I was young, I started singing songs that matched my voice. But when I heard "Misty Blue"... [singing] "Oh, it's been such a long, long time"... my voice sounded so much like hers... [singing] "That I just can't get you off my mind... Misty Blue" – it was like bingo, Gladys Knight, that was me.
There are probably young girls in their bedrooms now singing Angie Stone, thinking the same thing. It must be nice to pass that on.
There might be a couple of little girls who say, "Hey, that's the sound of my voice, I like the sound of my voice". It was very natural for me, I would gravitate to these women. Which is why people started saying, "Oh my god, she should play Gladys Knight". And now I've lost the weight, I must look like 25 or 30 years old!
On that note, what's beauty?
Beauty is in the eye of the beholder – I couldn't say it better. But a beautiful spirit, a beautiful energy – I don't think that anything else is very important. When you have all the qualities that make a person feel beautiful, the outer beauty is just the icing on the cake. If the inside of the cake is not good, the whole cake is bad.
You've been on the scene since the early Eighties. How have you stayed relevant?
By not falling into the trap of being something you're not. I think there's a natural progression that comes with age. But when we grow old, we must remember that times change, things rearrange, money gets funny and things go strange.
Angie Stone, aged 52, is an American R&B and soul singer-songwriter. She has sold over five million albums worldwide, with hits such as “Wish I Didn’t Miss You”. She lives in Atlanta, Georgia, with her son and partner, and returns to the UK later this month for dates in London, Manchester and Brighton