You will need four buttons. Rowan used #BF8847 from Bedecked in the UK.

Finished measurements:
Bust Circumference at undearm:
36(39.5, 43.5, 47, 51)“ 91(100, 110, 120, 130) cm
Finished length: 22(23, 23.5, 24.5, 25)” 56(58, 60, 62, 64) cm
Sleeve to underarm: 17.5(17.5, 18, 18, 18)“ 45(45, 46, 46, 46) cm

Yarn used:
Rowan Kidsilk Haze - used double-stranded
Liqueur 595 - 10(11, 12, 13, 14) balls