JNF stamp with a Star of David on bottom left depicting Herzl's tomb in Vienna is courtesy of Hayim Shtayer and part of his collection. Around the tomb are arranged the symbols of the twelve tribes.
This blog (by Zeev Barkan) is dedicated to the Star of David, its history, its various meanings and usages in different cultures. It includes thousands of pictures of Star of David, six-pointed stars, hexagrams, Solomon's Seals, Magen Davids and yellow badges,and served as a resource for three books and four art exhibitions.