And unfortunately, probably the best way to insure it actually is album is to buy a bulb. Seed from seed exchanges are likely not album unless they specifically say hand pollenated. Usually they are donated by well-meaning members who think open pollenated album will breed true. Not.
Martagon album seed will always be blonde.
Left: regular martagon seed. Right: martagon album seed.
But just to confuse things: not all blonde martagon seed is martagon album. Nor are all white martagons L. martagon album. I have a seedling of Amelita x Super Tsing that always produces blond seed.