1“ squared phosphorus bronze practice plate in 1.5mm thick material. Fits nicely in your vise jaws without workhold. 
Lightly scored lines set for setting 2.0mm stones or smaller within the square.  
You can certainly set them on the cross-section of the lines as well with bigger stones.  
The actual lines leave room for engraved cuts on each side to create more complex settings.  
Great for doing a box setting with imitation cuts, star settings, and even pave straight line.
With the lines already on the plates you can focus on alignment and cuts, making the most of your practice time.
There are now 2 additional plates for 1.8mm and 2.0mm stones (lines are just slightly wider to allow for onglette cut lines for pave practice) however you still get the same assortment of stones for all 3 practice plates.

Stone Setting Plate A has 64 squares suited for 3mm stones
Stone Setting Plate B has 81 full squares and many partial suited for 2.0mm stones.
Stone Setting Plate C has 100 full squares for 1.8mm stones.

Kit comes with:
- practice plate
-10x 3.0mm stones
-20x 2.5mm stones
-30x 2.0mm stones
-20x 1.8mm stones
**stones are best quality CZ which can be fired in place using Fire Coat (boric acid + denatured alcohol)

No refunds or exchanges 

When you go to stone setting or engraving schools you’ll find nearly all use phosphorus bronze unless they can’t get it or they won’t pay for it because it is more expensive than brass. The practice rings are usually bronze.

Why?

Phosphor bronze is an excellent practice metal for stone setting and hand engraving, particularly when the goal is to develop skills that will later transfer to precious metals.

The main reason is that it gives you meaningful resistance under the tool. It doesn’t feel excessively soft or mushy.

• It cuts cleanly with gravers. A properly sharpened graver produces a defined chip and crisp cut, making it easier to see whether heel, angle, pressure, and hand position are correct.

• It provides useful resistance. Copper can be so soft and grabby that it doesn’t always develop the same control needed later in sterling or gold. Phosphor bronze gives more feedback.

• It holds detail well. Bright cuts, borders, beads, stippling, engraving and small decorative elements remain relatively crisp.

• It’s particularly good for bead and pavé practice. The metal has enough strength around drilled seats that you can practice raising and moving beads without the surrounding metal simply collapsing.

• It’s useful for flush setting. Learn to cut an accurate seat and deliberately move metal over the girdle rather than relying on extremely soft metal to compensate for a poor seat.

• It work-hardens. That’s actually useful training. Repeated manipulation changes how the metal responds so you learn that metal has a working history.

• It’s inexpensive. You can drill dozens—or hundreds—of holes, break gravers, cut bad seats, ruin layouts and start over without practicing those mistakes in sterling or gold.

Why I’d choose it over brass

Ordinary cartridge brass contains a significant amount of zinc. It can have a different cutting character and, especially for torch work, introduces the issue of zinc oxide fumes when overheated.

Phosphor bronze is principally copper + tin with a small amount of phosphorus, so you’re practicing on a copper alloy without relying on zinc as the principal secondary metal (which is what the practice rings generally are).

What is the phosphorus bronze practice sheet seems too hard to drill?

I buy 510 or 5191 which is not spring hardened. However sometimes the metal can be harder than expected.  So if you know you aren’t doing anything wrong in your process, try annealing the metal.

Phosphorus Bronze Annealing Tips:

1. Place the piece on a soldering surface and use a neutral-to-slightly reducing flame. For a larger sheet, use a flame large enough to heat the whole area rather than concentrating a tiny hot spot.

2. Keep the torch moving continuously. Start farther away and bring the heat up gradually. Sweep over the entire piece so the temperature rises uniformly.

3. Watch the metal rather than one isolated spot.As you approach the annealing range, you’ll see surface oxidation develop. In subdued light, you’re looking for the very beginning of a dull red, roughly in the neighborhood of 900–1,200°F / 480–650°C depending on alloy, temper, thickness, and how complete an anneal you need.

4. Don’t keep pushing the color brighter. Once the entire working area has reached the appropriate temperature, remove the flame.

5. Allow the red heat to disappear, then quench in water. The quench doesn’t soften it—the heating cycle does. Quenching is primarily a convenient way of cooling the piece.

6. Remove the oxide as appropriate for what you’re doing next. Expect considerably more visible oxidation than you might see with silver.