You are correct in the calcium uptake enhancement through full spectrum lighting. Also through a calcium rich diet. That would include foods such as almonds, apricots, bok choy, broccoli, eggs, cabbage, figs, carrots, kale, mustard greens, oats, tofu, sesame seeds (unhulled), watermelon, parsnipss to name a few.
To synthesize calcium there must be a balance of D3 and calcium levels in the birds body. This is enhanced by feeding pellets and the use of lighting. I suggest you get your bird's calcium levels checked at least once a year by an avain vet.
According to the Phoenix Landing people the use of cuttlebone, oyster shells and mineral blocks are not recommended -- they are inefficient, unnatural for parrots and their sources are often polluted.