QUARTZ BLOCK

Everything else the Mason sells comes from Overworld stone. Quartz block breaks that pattern: the material behind it only generates in the Nether, so a villager who has never left his village is somehow the easiest way for a player to get some without going there themselves.

It is also the trade he saves for last. Nothing else on his list needs a higher tier than Master, level 5 of five. A mason who has just taken the job is nowhere near ready to offer it.

Just the Mason, and only once he reaches master: 1 emerald buys 1. No other profession lists a Nether sourced building block on its table at all.

The price is fixed rather than rolled within a range, so a second Master tier mason quotes the exact same number. What differs villager to villager is only how many uses are left before the next restock.

Quartz Block sells for as little as 1 emerald, from the Mason at the Master tier, and 8 of the other 9 cost less. The price is fixed rather than rolled, so a second Mason will quote you exactly the same.

The Mason at its master tier asks 1 emerald for a quartz block. 8 of the 72 villagers that pay emeralds, emptied out:

a compass against 24 flint for the same 1 emerald, 24 times the carrying, and the shortest wait is the Fletcher at 37.5 real seconds of shelf, gathering not counted.

A Mason climbs the same five tiers as any other job villager, and this is the trade waiting at the far end of that climb: Master, level 5 of five, 250 trading experience from the bottom. Every tier below it sells stone and terracotta instead.

Once unlocked, the offer holds 12 uses before it locks, restocking up to twice a Minecraft day back at his stonecutter. Breaking that stonecutter at any point along the way before master resets the whole climb, so a mason worth this trade is one worth protecting.

12 uses clear the slot, then a 2 real minute wait for the mason to walk back to his stonecutter and refill it. A Minecraft day is 20 real minutes and covers two of those refills.

That is 24 quartz blocks for 24 emeralds in a day of standing there, or the same total spread across however many real days you actually check back in. Getting him to master takes far longer than draining the slot ever will.

Once a mason is at master, clear his slot in one visit: 12 emeralds for 12 blocks. Getting him there is the actual project, not the buying.

Fund the climb along the way: the same mason buys 10 clay balls for an emerald at an earlier tier, which pays for a good chunk of this trade before you ever reach it.

Also on the Mason's list: brick, stone, chiseled stone bricks, granite, andesite, and diorite.

Four quartz make one block, and the block is the cleanest white in the game short of concrete. Unlike concrete it needs no dye, and unlike snow it does not melt or turn to powder, so it is the default when a build wants to look finished.

The quartz itself only comes from the nether, which is what the price is really about. A villager selling blocks is selling you a trip you did not have to take.

It cuts three ways from there: two blocks give two pillars, four give four bricks, and chiselled quartz comes from slabs. All four look different enough that a build made only of quartz still has texture in it.