Authentic Maltese silver filigree will always bear a hallmark. Look for the '925' stamp which indicates sterling silver. Additionally, established shops in Valletta will readily provide certification of authenticity.
In standard retail shops, boutiques, and artisan centers like Ta' Qali, prices are fixed and haggling is not appropriate. However, if you are visiting an open-air market like Marsaxlokk, light, polite haggling is sometimes accepted.
The island of Gozo is renowned for its traditional lace-making (Bizzilla). Victoria (Rabat) in Gozo has several dedicated craft shops where you can guarantee the lace is handmade locally and not imported.
Yes. Major artisan stores like Mdina Glass and Bristow Potteries are very accustomed to international tourists. They offer professional international shipping and insurance directly from the store.