Identifying authentic Yixing teapots can be tricky, just like all antiques. Yixing teapots are unique in that they are enjoyed both for art and utensils. What's interesting 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 teapots (majority of them are fine artwork and quite many are masterpieces with a few "Peerless treasures"). Based on my experience, Yixing teapots can be divided into the following 6 categories:
Non-Yixing (most modern produced commodity) teapots
Old (Commodity) Yixing teapots ($100-$300)
Fine Artwork ($200-$2000)
Peerless treasures (>$100,000)
We recommend tea drinkers and collectors start with old Yixing teapots (made before 1995) for the following reasons: First, compared to modern artwork, old pieces are actually cheaper. Second, 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 Non-Zisha commodity (cheap) or Zisha Fine Artwork (expensive).
There is an Impossible Triangle: Well-crafted newly Made; Cheap or Under $200; Authentic
Please be aware of Type 1 and Type 2, and fake TianQing clay teapots (they are all over the internet).
See Yixing Zisha Clay Teapot: Fake vs Authentic (2 min read)
Six Types of Teapots
Type 1 Chemical Teapots
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. They are machine-made, but claim to be hand-made. See this Yixing Zisha Clay Teapot: Fake vs Authentic
The words read of Tianqing clay of Raw Ore. But it is Cobalt blue - Chemical teapots in fact.
Unfortunately some of them look similar to some ZhuNI clay (DaHongPao) teapots. If it is new, below $200, and brightly red, most likely it is Chemical teapots.
See below Chemical teapots (LEFT) vs DaHongPao (RIGHT). It is very hard to tell.
Type 2 Non-Yixing Teapots
(Most modern produced commodity after 1990s) teapots either use Non-Zisha clay or of very poor quality. They may not be toxic, but can not have the Zisha appeal either. The reason why I put modern commodity so called Yixing Zisha teapots into the Non-Zisha category is the high cost of the Yixing Zisha clay. In the year 2014, my antique mentor went to a famous Yixing Zisha clay provider. The cheapest Zisha clay costs $300/pound. What kind of teapots can you buy below $100? In 2015, I went to a Yixing Zisha shop owned by a craftsman. $130-180 are cookie-cut made. $220 are semi-cookie-cut. Unfortunately some of these non-Zisha teapots look similar to real Yixing clay.
Type 3 Old Commodity Zisha Teapots
Type 3 Old (Commodity) Zisha teapots are those made before 1995s. At that time and most of the time before, commodity grade Yixing Zisha teapots were cheap. They may not look as beautiful as those of Fine Artwork or masterpiece. But they are made of real Yixing Zisha nonetheless, and therefore can have the Yixing Zisha appeal.
Type 4 Fine Art Work
Type 4 are pieces of fine artwork made in the past or modern times. They are usually made of good quality Yixing Zisha clay, aesthetically appealing.