Crystal saw can boost (3) but it cant be used to build new rooms e.g garden at level 65 and your construction level is 62 .
Crystal saw is obtained from a quest called The eyes of glouphrie .
But however stews can boost up to 5 , using orange spice on a stew .
However it is difficult to get boost(5)as it is gives randomly boost -5 to +5 (yes sometime it can decrease your construction level .
And btw s using kitten is annoying as fuck to get spices , but there is script on osbot that get for you spices but i think it is +VIP .
I suggest you to spend more 1M and get from 60 to 65 as it is faster and less husstle .
Good luck