I adore glass and it's something that I am always on the lookout for when I go 'tiquing. I recently found a massive collection of depression glass, something that I have always admired, but didn't know enough about to purchase confidently.

I bought the lot - and it's been quite a process learning the ropes. There were so many manufacturers and not much hard-core information. I'll be the first to admit that I made a few mistakes, and now I am incredibly careful about not calling something Fenton if I can't guarantee that it is. I'll say it has a "blue-ish tint" and when possible, show another piece without that tint for comparison.

You really have to know some basic fundamentals and history of American glass manufacturing to avoid reproductions - some of which can be quite convincing in appearance. My little guide isn't a substitute for a comprehensive, specialized sourcebook (and there are many) but it is a quick jump start, especially since most of this isn't marked.

As for "original labels" I am always a little leery about that, but that's a personal opinion. I find the oddest things in my travels, and I wouldn't be surprised to stumble upon a full sheet of original labels. How well glued on are they, and is there residue from the back of the label on the glass? Prior to photographing anything, I usually give anything a good cleaning.

My best advice? Ask questions and ask to see close-up photographs. Ask if the hobnails are intact. Has the dish or goblet been tested for leaks? That's easy to do - just add water...and wait.

The opacity milky, or "moonstone" depression glass is from adding ash or tin oxide in the firing process. Other coloring agents or even a quirk in the firing process can cause the glass to range in hue - blues, greens and even blackish marks aren't uncommon.

But - just because one piece of opalescent has a blue cast - does not guarantee that it is Fenton, either. I noticed that when I photographed six candlesticks. I tried to match them up so that the pairs looked right, but one kept jumping out. It was so blue, it didn't fit. Too bad I didn't have two of those ;)

Pressed glass refers to the mold. Typically, you will notice lines running across both sides of a piece. The key to distinguishing an authentic vintage piece from a good reproduction are the "straw marks" on the bottom. These are imperfections that look like straw - long, imperfections or lines - and are clearly visible. IF you find pressed glass with mold markings along the bottom of the piece - it's a reproduction. IF you find a piece that looks absolutely perfect with no lines, waves, or bubbling - it's a reproduction.

Look for imperfections in the glass - striations of any sort, especially on handles & lids, and check to see if there's any unusual waves in between the knobs. Does the piece have bubbles in the glass? Bubbling should not be uniform in size or shape, but random throughout the piece.

Why are there such a broad range of prices for the same piece ofdepression glass on eBay? Well, this doesn't always have to do with the quality of the piece. And other times - it does. I learned that chips can be hidden - underneath the lid, for example. When purchasing from a seller who is NOT a specialist - ASK. ASK if the lid has been checked UNDERNEATH for hairline cracks. ASK if the lid feels smooth to the touch.

On eBay - it's all about supply and demand and that's also part of the fun. Sometimes there's an abundance of some pieces that have a higher listed value. Other times, a little piece that isn't even listed seems to be less plentiful, and therefore more expensive. While I do a lot of research in the library, I always pay attention when meeting with avid collector. True collectors are a gold mine of information and love talking about their hobby and sharing their knowledge.

That's the best tip from Twinkie's toolbox: When you meet someone who knows her stuff: HAVE GOOD EARS. Just be quiet and listen. The best resources for learning are other people with more experience. Remember: People love to talk about what they know best! Hope this helps & happy hunting on eBay!