I do realize that there may be a large percentage of home poker players that have never stepped foot in a real casino or poker room, so they may not be fully aware of what a true casino poker chip is like. So, I will try to explain what you will find and then will provide some sort of clarification in regards to what retailers are calling "casino quality poker chips".
Casinos generally use two types of poker chips, clay or ceramic, with the majority of the chips being clay poker chips.
The term "clay" is a misnomer, though, since the material that the chips are made out of are not real clay. If the chips were real clay they would be much too fragile to be used as much as they are used in casinos. They would wear down or break apart from just a fair amount of use. Instead, the material is a composition of polymers that set with high heat and possibly some earthen materials. However, all casino clay poker chips are painstakingly produced through a process of compression molding. This is a multi-step process. The first step is a simple compression of the base chip. The base chip is cut out to allow stripes around the outside of the chip and then it is pressed again. Finally, an inlay is placed in the center of the chip and it undergoes one last pressing. Due to the amount of labor used to produce these chips, clay poker chips are very expensive and there are only a handful of companies worldwide that produce true compression molded clay poker chips.
During the last couple years many retailers have marketed their poker chips as "clay poker chips". However, they are NOTHING like the real clay poker chips that are found in casinos. If you are looking for these to use for your home game, make sure you look for the brand name, "Paulson". There are some Paulson clay poker chips available to purchase for the home market, but these can not be customized.
The other casino poker chip style is a ceramic poker chip. These are completely different than clay poker chips. They are made from a single composition material, which while is not fully ceramic, they retain qualities of a ceramic material. Ceramic poker chips are flat on the faces due to the printing technique used to put the image on. The image is applied through a heat press technique and is not a label, sticker, or paint.
One thing to note about casino poker chips, whether they are clay or ceramic, is that they practically never weight more than 10g. If a retailer is advertising casino quality poker chips but they weigh 11.5g, 13g, or more, then they definitely are not what they are claimed to be.
One other thing that can be a big indication is price. If the price is $0.10-0.40/chip, they are not real casino quality chips. The types of poker chips used in casinos (clay or ceramic) require a lot of labor so the price is high and will always be high.
Now, regarding retailers that claim they have "casino poker chips", please be aware. I would guess that up to 90% or more of these chips are NOTHING like real casino poker chips. So, be careful when you decide to purchase your next set of poker chips.