Looking at the Steam Community page on my inventory, I can see that any community item such as a profile background, trading cards or emoticon can be converted into a certain amount of gems.

enter image description here enter image description here enter image description here

However, I never entirely understood what defines this value. What I have noticed is that the more popular its respective game is, the more valuable the item will be in gems. But if that's the case, what defines that game as being popular? How many times it's been purchased, the amount of reviews? And what about any base values?

How are the gem values calculated?


There seems to be a "complicated" way to do this. WARNING: The following might differ for some games and versions. This is an estimate by this wikia.

Similarly, the gem value of a set's emoticons and backgrounds appears to be equal to the number of cards in the set * the gem value of normal cards / 2, rounded up to the nearest multiple of 20. The value of a foil is ten times (10x) the value of the normal card. This applies to all sets. The value of an emoticon is equal to the value of a background crafted from the same set.

Emoticons and backgrounds associated with Valve (Valve games and summer/winter sale trading cards) are always worth 100 gems. Free-to-play games (which drop cards based on how much one pays) generally have high-value items as well. In general, the more cards in a set, the lower the value of the items and cards themselves. The inverse is also true. Only trading cards, emoticons, and backgrounds can be turned into gems. The process is irreversible.

So to sum this up:

  • Only trading cars, emoticons, and backgrounds can be converted into gems

  • Emoticons and backgrounds that deals with Value will always be worth 100 gems.

  • The gem value of a emoticon/background is based on the number of the cards in its respective set times the gem value of normal cards then divided by two and finally rounded to the nearest multiple of 20.

  • The gem value of a foil card is 10x of its normal version

Formulas could be found in the wikia link above as well as more information.

  • I have now just realised that my question here is in fact a duplicate (however the question doesn't have an accepted answer). You may want to post your answer now on the earlier question as the answers there lack as much detail as yours.
    – user114997
    Oct 3 '15 at 16:21
  • Yay! Double the rep! Oct 3 '15 at 17:53