100% Best Malt Red X malt @ 1.050 is a beautiful red color. Agree that roasted barley finely ground is too.
CaraRed will add some reddish amber color and would help deepen a 100% Red X malt grist - it has a pleasant,, smooth caramel flavor.
There is nothing that looks as vibrantly red as a 100% Red X beer at 1.050 or so OG, once it drops completely clear. But the flavor of that beer just isn't for me. Red X tastes in the ballpark of a very dark Munich spiked with a bit too much Aromatic/Melanoiden malt. It's just too strongly rich for me to drink in any great amount. Sure looks great in pictures, though.
Roast barley and CaraRed will help push a beer in that direction, but at best you will get a reddish amber. One other way to get brilliant ruby red color in your beer is cherry juice if adding fruit is an option.
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