You will need 3 buttons. Rowan used # BN1745 3/8 - 1/2” (1.1 cm) in mother of pearl.

Finished measurments:
Bust circumference: 37.75(41.75, 45.75, 49.5, 53.5)“ 96(106, 116, 126, 136) cm
Finished length: 19.75(20.5, 21.25, 22, 22.75)” 50(52, 54, 56, 58) cm
Sleeve to underarm: 6.25(6.25, 6.75, 6.75, 6.75)“ 16(16, 17, 17, 17) cm

Yarn used:
Rowan Fine Lace
A. 922 Cobweb - 3(3, 3, 4, 4) balls

Rowan Kidsilk Haze
B. 642 Ghost - 4(5, 5, 6, 6) balls