I'm planning to push real jewelries provided by my friend's dad, and I was wondering how do you guys prevent getting scammed when selling $1000+ jewelries online?

Ask the seller about the details...duh.

Use signature confirmation and insurance.

First off, make sure that is in, in fact, real. A lot of people that have "real" jewelry don't what they have. Take it in, get it tested by a professional (if you aren't one). Then you have proof on your end that it's real.

Then, make sure to use the confirmation / signature that is mentioned above.

Sounds like no one read your question right LOL! You said you are going to selling jewelry and you want to avoid getting scammed by your buyers right? First of all, make sure you have your Paypal account setup to ONLY ACCEPT Verified and Confirmed Paypal email addresses for payment. When you sell an item, go to Paypal and make sure it says "Confirmed" under the buyers name and address. If it says "Confirmed" then you are covered under the Seller Protection rule. You can then ship it to that Confirmed Address Only in Paypal. If the buyer listed a different address to ship to, let him know you can only ship to the confirmed address. If he does not agree, then cancel the sale and refund the payment or make him pay via another method like money order.

ALWAYS ship your item of that value via UPS with Insurance and Signature Required.

DO NOT under any circumstances ship to Unconfirmed Addresses as you will not be eligible for Paypals Seller Protection.

good luck with the jewelry, i have a good hook up on a name brand...but ebay restricted my account, because they think its fake, even after i submit receipts etc. to prove they are genuine