^SIS, if you are not yet familiar with these -- buy from ACCESSORY LAB at Power Plant Rockwell.
Although, I haven't been buying from there lately -- Rodina the shop partner - owner of the crystals has doubled her prices. Some of her items are unreasonably priced.
Atong in Binondo sells at prices approx 30percent less.
You do not need big blocks -- big or small, whatever the quality -- same same energy yan. Must be authentic & you gotta condition your crystal/s.
Sis, get hold of that Crystal Bible Vol.1 book of Judy Hall.
You can go to Acc Lab, familiarize yourself with the crystals you want -- tignan mo lahat ng specimen of say the black tourmaline, & do not be shy to ask the girls why the difference in prices. That way, pag tapat mo kay Atong -- you will get a good price coz you know what to look for & what the prices are approximately.
You must educate yourself 1st. Ang dami na kasi selling fakes.
I see a lot of quartz sold as citrine, amethyst, rose quartz, etc.
Madami "reconstituted" -- mga molded beads from colored bonded particles .
Like a lot of "bronzites" I see around in Manila now.
Sis, I started by concentrating on 1 or 2 crystals at a time. Absorbed as much as I could, looked & touched. Tapos, buy.

. Then, onto the next crystal.
Be careful with black tourmaline -- the fakers sell hardened charcoal as black tourmaline.
Or those reconstituted colored ones. Haynako.
When you buy Selenite -- check that it looks like there is water trapped inside -- hindi basta white porous -- baka gypsum lang or tawas. Ngek. The entire block will not have "water trapped inside", but there must be such a portion. It is good for lightening up places & people -- para hindi "mabigat" a place.
Easy to get educated on citrine. Dami specimens to learn from.

Good luck, Sis.