There are 12 Angels of the Gates of Time, 12 Doors, 12 Tribes, 12 Foundations of the New Jerusalem and 12 Precious Stones in the Breastplate of the High Priest. These all corresponds with 12 months of the year.
The 12 Foundations that the Church of the 12 Ages must be built upon is made of a precious stone and represents the main Angel that rules that Foundation and Tribal Gate (Gate of Israel).