Unfortunately I've no advice on the ring itself. Just a cautionary tale on how not to propose.
I worked in a restaurant/nightclub a few years ago. One evening a couple came in. They seemed to have been out for the evening already when they arrived. The boyfriend of the couple made a few trips to the bar and each time downed a double at the bar whilst waiting for his drinks. It was noted by the bar staff that the body language was getting tense at their table. Raised voices were noted a while later, followed by a full blown shouting match. By the time staff approached to calm the situation the female was sat at the table in tears whilst the male was angrily walking around shouting whilst scanning the floor behind his girlfriend. The whole episode had clearly disturbed nearby diners. A member of door staff tried to calm the boyfriend, asking him to step outside to calm down and explain the problem. He refused and continued shouting and ended up being forcibly ejected. Outside he still wouldn't calm down and there was no way he could be let in until his attitude was more measured and not liable to disturb everybody in the building. Instead he picked a fight with the door staff, this was noted by passing police and he was arrested and taken to the police station without his girlfriend.
Meanwhile other staff comforted the girlfriend and got her to explain what had occured. It transpired that he was drinking so heavily to pluck up the courage to propose. He'd clearly misjudged and his girlfriend was at best noncommital. This led to the argument and in his anger he threw the engagement ring at his girlfriend but missed her completely. He had been wandering around looking for the ring. It should have been somewhere on the floor, though several thorough searches of the area yielded no ring. It was never found, at least not by the couple or by staff.
What had started out as a plan for a romantic night out culminating in a proposal of marriage, ended in drunkenness, anger, argument, loss of an expensive engagement ring and arrest. Whether they ever got it together and now laugh at the events of that night I don't know. It certainly could have gone more smoothly.
Hopefully whatever ring you choose, you'll get the response you desire. Just remember, one drink to stiffen your resolve should be enough. Good luck.