Now that you're engaged, you're going to have all your friends and family ask to see that rock. After they are all done swooning over it, you might have a few of them ask questions that you won't know how to properly answer.
How can I answer awkward questions about the cost and size of my engagement ring like "How many carats is that?!" or "How much did that cost?"
You're going to get these types of questions, and even though it is an uncomfortable situation, it's more uncomfortable if you give no answer at all. One way to deal with these awkward inquires is to give a vague response. If they are asking you for the cost of the ring, try making a joke out of it by responding with, "It's priceless!" (After all, you might not even know how much your guy spent on the rock.) If they ask you how big it is, try something like, "It's enough for me to say yes!" Plus, an engagement ring is a symbol of your man's love so in a way it really is priceless.
This way you're not being rude by completely shutting them down, but you're still acknowledging their question. It might not be the answer they were expecting, but hopefully they will get the hint and not ask again.
And try not to get offended, your nosy friend or family member is probably just as excited as you are about the upcoming wedding.