The down-on-one-knee, diamond-engagement-ring proposal is a huge part of our culture that we see everywhere – in movies, in our own proposals, in our friends' Facebook selfies. But how much do you really know about the diamond engagement ring? Can you tell fact from fiction in this list of common beliefs? Test your knowledge!

While engagement rings have been around for a long time, the iconic diamond ring is a pretty recent development. Rings made from precious metals and other gemstones, such as rubies, emeralds, and sapphires, were more common in the past. It wasn't until the 1930s and 1940s that diamonds took off in popularity.

Back in the day, women were expected to be virgins when they got married. But if an engaged couple had been intimate before the big day and he broke it off, she was left in a bad spot. At that time, she could actually sue him under "breach of promise" laws which started dying out around the time diamond rings gained popularity. The idea behind the promise was that if he walked out, she could still keep the ring!

When diamonds were starting to enter the engagement ring scene in the 1930s, there was of course an iconic advertising campaign to move that trend along. With the slogan, "A Diamond is Forever" in 1947, DeBeers kicked off a massive cultural phenomenon. It didn't take too long for Americans to fall head over heels: in just a few decades, more than 80% of engaged American women sported diamond rings.

There are savvy investors out there who swear diamonds are the new gold. But for most of us, a diamond engagement ring is an emotional symbol, rather than a retirement nest egg.

That said, diamond rings have earned an unfair reputation as poor investments. The common myth is that when you buy a diamond ring, it immediately depreciates. So if you buy a $5,000 diamond engagement ring and try to sell it to the jeweler next door, and he offers you only $3500 for it, you feel like you got a raw deal.

But here's the thing: the original $5,000 you paid for the ring included the first store's expenses for keeping it in inventory over time, plus the profit it needs to make to stay in business. The same thing happens when you buy a car from a dealership: the car doesn't depreciate in value as soon as you drive it off the lot – you have to figure the dealer's profit into the selling price.

With diamonds, there's a balance between their initial cost and their long-term value. More affordable stones are still likely to hold their value over time, but larger, more expensive stones will do so more efficiently since they are rarer. So budget-conscious shoppers should manage their expectations realistically, perhaps looking at more affordably priced rings that also have a trade-in option.

Learn how My Trio Rings keeps engagement ring prices affordable by cutting out the middlemen.

There's a rumor that it's common to get duped with a cheap imitation when buying a diamond ring – especially when you shop online. But it's actually very easy to weed out the rare scams. Any reputable seller will offer you a certificate of authenticity and for larger purchases its wise to have one from an independent third party such as the Gemological Institute of America (GIA) – so you know it's the real deal.

You can also do a few quick, DIY tests on any diamond ring to verify its authenticity. For the "fog test," simply hold the stone close to your mouth and breathe on it. Diamonds can't hold heat and should clear up immediately; fake stones will remain foggy. For the "newspaper test," hold the stone over a piece of fine print on a newspaper. Diamonds refract light in a way that should prevent you from reading the print below; fake stones will allow you to read the words.