There are no absolute rules which dictate which pin to use for a particular type of lace. Suit the thickness of the pin to the thread you are using to produce a result which you find pleasing.

17mm x 0.45mm x 25g packet (white) brass 'Duchesse' pins.

 £6.50

30mm x 0.50mm x 50g box nickel plated pins.

 £4.00

26mm x 0.58mm stainless steel, box of 225 pins.

 £1.75

14mm x 0.60mm nickel plated, box of 800 pins.

 £2.50

18mm x 0.60mm x 25g packet nickel plated pins.

 £1.75

26mm x 0.65mm x 25g box yellow brass pins.

 £2.50

26mm x 0.65mm x 100g box yellow brass pins.

 £6.00

26mm x 0.75mm x 100g box nickel plated brass pins.

 £5.60

38mm x 1.05mm mild steel nickel plated, packet of 18 pins.

 50p