The item filter editor guide goes over how to figure out the mods you need. Check prefix and suffix for the one you want.
Once you have the stat from the site, remove the spaces, and convert + to Pos, and % to Pct.
Dump the current Stats (see the Dev tab guide) and you'll be able to verify the stat is correct.
So for example, if you were looking for the + bow gems stat, you'd find it on the prefix page, then change the stat of "Local Socketed Bow Gem Level +" to "LocalSocketedBowGemLevelPos". If you search for that in the dumped stats, you'll find the entry to know it's right, "[529] [LocalSocketedBowGemLevelPos] [local_socketed_bow_gem_level_+] []"
Do the same thing for the Cold, and you'll find it.
