Question: are steam gems worth it?
Answer: 20 gems / 3 cents for a card it's more worth it. ... An item Sack of gems is worth a few tens of cents on Steam Market (at the time of writing it's around €0,45, which seems to be the long-time median price). So it probably won't be worth it to buy items worth 100 gems for conversion and reselling as sacks of gems.