ok ! i know about all but diamond expansion in the sense of how to get them . i have seen diamond expansion but not sure at what point they are available . i'm just into industrial age
This post:
https://forum.us.forgeofempires.com...d-Expansions-2-0&p=47682&viewfull=1#post47682
describes all possible expansions and their costs. It does not mention that two new diamond expansions become available in eac h age. So in bronze age the first two are available (200 diamonds, 200 diamonds), in the iron age the first four are available (200, 200, 400, 400), in early middle age the first 6 are available (200, 200, 400, 400, 600, 600), etc. Costs don't keep scaling up, but see the linked page for how costs do go up. You can always buy the expansions available in previous ages, if you haven't yet, and the two new ones available in the current age.
So by industrial you would have available: 2 for bronze, 2 for iron, 2 for early middle, 2 for high middle, 2 for late middle, 2 for colonial, and 2 for industrial, or 14 diamond expansions total, at the following costs: 200, 200, 400, 400, 600, 600, 600, 600, 600, 600, 600, 600, 600, 600.