Assorted Japanese tailors chalk
Option 1: Chakoner Heart Shape
The clicky rotary dispenser is so far the most precise chalking method I've come across. It marks well without spilling chalk all over your fabric. Comes in a heart shape, with a useful eraser brush at the top. Refillable.
Option 2: Triangle (Musubi) Shape
Smooth dispensing tailors chalk. Easy to mark and easy to erase. Refillable by removing the cap.
Very limited quantities available, these were brought back from my last trip to Japan.