Open8@Chin-PalmBack Open8@NearSideChinhigh-PalmForward

Etymology
Presumptuously, it's a transformation of a sign 'Good' to 'Luck' in this backward order.

Luck <--- Bastardized the word "Fortune" to "Luck" <--- Fortune <--- Good <--- (Alternative #1) Rewarding for speaking correctly hence the gesture for "You speak correctly, good!" (Alternative #2) A gesture for warm air out of mouth which indicate that it's "good". (Alternative #3) Affordable to buy food. Mouth for food to eat, hand downward for a gesture of holding a bag of money.

Look at each international sign language for the transformation of the word "Good".

French: "Bon" - http://media.spreadthesign.com/video/mp4/10/14618.mp4

Spanish: "bueno" - http://media.spreadthesign.com/video/mp4/5/14611.mp4

Ukrainian: "добро" - http://media.spreadthesign.com/video/mp4/31/110480.mp4

Polish: "dobry" - http://media.spreadthesign.com/video/mp4/19/59015.mp4

Production

 * Turn the hand at the wrist to face outward and slightly to the side of the face.
 * Turn the hand at the wrist to face outward and slightly to the side of the face.
 * Turn the hand at the wrist to face outward and slightly to the side of the face.

Noun

 * 1) luck

Adjective

 * 1) lucky; fortunate