I am not an expert in Iznik ceramics by any means, but know that it is highly desirable.
What is the history of the piece? What leads you to believe that this came from Turkey? That it is Iznik? Is there a signature? Marking?
The only thing I do know for sure about Iznik is that it is made of quartzite (semiprecious stone) and that the beautiful patterns are painted/dyed directly on to the quartzite base, fired, then a clear glaze is painted then fired on. That is why their coloring lasts for centuries! Also, because of the quartzite it makes it perfect for indoors and outdoors. Because of the durability of quartzite pieces they don't "age" like other tiles.
If you are wanting to establish it as the "original" Iznik from centuries ago, you would need a hands on inspection from a specialist AND an analysis of the quartzite base to determine materials.
So, do your pieces have highs and lows where the colors are added? Do they appear painted on? If so, not true collector Iznik!
Maybe someone else will chime in here!