Casual Business attire specifics for men: 

• Ties:
  Ties are generally not necessary for business casual, but if you are in doubt, you can wear a tie. It never hurts to slightly overdress; by dressing nicely, you pay a compliment to your host. You can always wear the tie and discreetly walk by the room where the function is held; if no one else is wearing a tie, you can discreetly remove yours.
• Shirts:
  Long-sleeved shirts are considered dressier than short-sleeved and are appropriate even in summer. Choosing white or light blue solid or conservative stripes is your safest bet. Polo shirts (tucked in, of course) are acceptable in more casual situations.
• Socks:
  Wear dark socks, mid-calf length so no skin is visible when you sit down.
• Shoes:
  Leather shoes should be worn. No sandals, athletic shoes or hiking boots.
• Jewelry:
  Wear a conservative watch.  If you choose to wear other jewelry, be conservative. Removing earrings is safest. For conservative industries, don't wear earrings. Observe other men in your industry to see what is acceptable.