Step - 1) Draw a line AB = 6cm.
Step - 2) At A, draw a line AQ so that angle (BAQ) = 60°.
Step - 3) Cut AD at C such that AC = 6cm.
Step - 4) At B, draw a BP so that angle (ABP) = 180° - 60° i.e. 120°.
Step - 5) Cut BP at D such that BD = 6cm.
Step - 6) Join CD.
ABCD is the required rhombus.