Although it is the only "Gem-Knight" Fusion Monster without an effect, it is arguably the easiest to Summon as Rock is the most popular Type among the "Gem-Knights".
This card is easily Special Summon from the Graveyard by using the second effect of "Daigusto Emeral".
As there are quite a few Normal and Gemini monsters among the "Gem-Knights", a "Gem-Knight" Deck may use support for non-Effect monsters. This card along with "Gem-Knight Pearl" would be the only 2 "Knights" that would benefit from this support that are stored in the Extra Deck.
"The Earth - Hex-Sealed Fusion" can easily help Summon this card. It will not be substituting for a Fusion-material monster but rather acting as the Rock-Type material required, so all you would need is a "Gem-Knight".
You can use "Super Polymerization", to use a Rock-Type monster from your opponent together with one of your "Gem Knights" and Fusion Summon "Zirconia".
Use "Super Polymerization" in your Battle Phase, after all your monsters attacked and Fusion Summon "Zirconia" for an extra attack or possible OTK.