Not all gems can be enhanced during rituals on starting levels. The higher your level is, the more valuable gems you can merge in the totem:

Level - Gem's maximum rating

1-5 levels - 50.000

6-10 levels - 100.000

11-15 levels - 150.000

16-20 levels - 200.000

21-25 levels - 250.000

26-30 levels - 300.000

31+ levels - 999.999

Your ability to merge gems depends also on the number of the dungeon you're currently in. If totem is saying that your gem is too big to perform the ritual and your level is equal to gem's rating, then you just need to move to the next dungeon to get the totem with bigger capacity.