Identitying authentic Yixing Zisha clay teapots can be tricky, just like all antiques. Zisha teapots are unique in that they are enjoyed both their art work and usage. What's more is that "the more and longer it is used, the better it looks". Let's call this property as "the Yixing Zisha Appeal".
Over the years, I have collected over hundreds of Yixing Zisha teapots (majority of them are fine artwork and quite many are masterpieces with a few "Peerless treasures"). Based on my experience, Yixing Zisha teapots can be divided into the following 6 categories:
None-Zisha (most modern produced commodity) teapots
Old (Commodity) Zisha teapots ($100-$200)
Zisha teapots of Fine Artwork ($200-$2000)
Peerless treasures (>$100,000)
We recommend collectors collect old Yixing Zisha teapots. There are a few reasons for this. Firstly, compared to modern artwork, old pieces are actually cheaper. Secondly, old teapots usually have very good quality Yixing Zisha clay, which would have a good appeal property. Lastly, old teapots have high historical and cultural value.
Please note we intentionally left out "Modern commodity Yixing Zisha clay teapot" because it doesn't exist. If it is made after 1995 (we called Modern era), then because of the high price of the real Yixing clay it is either None-Zisha commodity (which is cheap) or Zisha Fine Artwork (which is expensive).
Please be aware of Type 1 and Type 2 and fake TianQing clay teapots (they are all over the internet). You will know after reading this TianQing Clay article
Chemical teapots are made of clay added with modern chemicals, usually have very bright colors. These chemicals are added to cover the bad appearances of the original clays. These teapots are toxic and cannot be used. Most modern cheaply-made Yixing teapots of all different colors and great looking belong to this category. I just listed a few pictures here.
Unfortunately some of them look similar to some Zhu clay teapots.