Minerals

ruby:
  enabled: true
  permission: ruby
  model_id: 1
  name: '&fRuby'
  events:
    block_break:
      drop_this_item:
        from_block: ruby_ore
        chance: 100
        min_amount: 1
        max_amount: 2
        cancel_on_silktouch: true #disables drop if the block is broken with silktouch

As you can see I created the block_break event which has drop_this_item as child element. This configuration makes ruby to be dropped from ruby_ore custom block. You can also change ruby_ore to a vanilla block, like I did with some other minerals (refer to the minerals.yml file)