This jewelry features flowers or scenes under glass. The pins are usually framed in brass or nickel silver. Some collectors call these goofus glass pins, while the correct name is reverse painted intaglio. Some of the finer ones are sterling and some are bakelite. Essex crystals are usually framed in gold or sterling. The backgrounds can be thin metallic foil paper (typical) or mother of pearl (older). I seldom find these pins in excellent condition. Generally, they are cheaply made and were never meant to outlive their original owners.