are you asking about the blue (+225% crit dmg and +45% block)? you can either find Legend items with these affixes as loot, use Obsidian to place these affixes on items, or use Dust to buy them out of the LegendEx and hope they come out with a Crystal affix.
they are hard to find/craft/get. if you have items equipped, like a farm build for example, with high Luck and maybe have Crystalline Set, this will improve your chances of getting an item with Crystal Affixes. using Obsidian Crystal will give you some random choices automatically, so doing it this way might be harder than getting a Crystal affix with the other 2 methods.
How can i get the 100% legend affix poison damage
do a search for @Emman Crystal Crafting Restrictions. it lists the affixes that can’t be rolled or that have restrictions on how they are rolled.
to answer your question, you can’t get Legend +100% Elemental Dmg. with Ruby. you have to find an item with that affix on it. if you are looking for an item with certain other affixes besides the ED%, just take a look in the LegendEx to see which items of any Class has the combination of ED% and other affixes you want on your build.