How many Pgems equals what runes?

As the title states, how many pgems does it cost generally to trade for what runes. Currently have around 23-24 Pgems and curious what 20-40 pgems would be able to trade for.

Thanks in advance.

seems like 40

Perfect Gems are worth one

Ist at the moment:
pricecheck.php?item=865059

40 for an

Ist is pretty much the standard for a long time.
40 is practical for trade as it's a full backpack.
For others runes, just use the runes comparison - but the more gems, the relatively lower the price.

To notice that perfect amethysts are 2 to 3 times more expensive - I typically trade 15 PAm for an

Ist.

Prubies normally come second, but their price is closer to the ones of other pgems than of pAms.