Hi gogo94! You picked out some really pretty bangles! We had a Ming's collector posting last year with some really pretty pieces. I hope she still lurks and comes back to comment. For me, I have a couple signed pieces and some I'm fairly positive are unsigned Ming's.
The first one I would feel definitely feel confident about being a Ming's. Stamp looks right, the style of the gold hinges, and the style of the jade all point to a Ming's bangle. The second one... could be, but I'm not as confident about it. Some Ming's were hand signed. I'd ask for a straight on picture of the carving on the gold band to see how well it matches other Ming's bangles gold patterns. For me, at that price alone, I wouldn't even be considering it. Ming's is a collectible sure, since they aren't making more... but for that price, you could get a really really nice jade bangle and/or custom a hinged bangle that looks very similar!