It's normal and is due to the non reflective areas in the surface that consist of the resin matrix. A "glossmeter", which electronically measures the reflectivity of a surface regularly gives a reading in the 50's for any quartz and in the 70's or 80's for a polished natural stone.

A square of a black quartz surface placed next to a black granite will be very noticably less reflective due to the resin in the surface.

That is good info to have. If I get quartz I can at least get into it with proper expectations. Thanks. Since you know about these things, may I ask if quartz is indeed as much stronger and non-porous than granite, and maintenance free, as it is touted to be? Or is the reality different?

vishg;

quartz surface is indeed "stronger" than most natural stone. However, the term "stronger" is misleading since the countertop user cares little about the mechanical strength of the material; he is much more interested in the hardness and most natural stones are harder or much harder than quartz surface materials.

quartz is non-porous so it is more stain resistant than many natural stones. However, the resin in the quartz makes it vunerable to heat damage.

In reality, staining in granite and scorching in quartz are both rare events and should only be a minor consideration for most users.

I always tell my customers to pick the material that has the look they want. SOme natural stones like marble and limestone warrant extra consideration as their durability and stain resistance is substantially inferior to granite and quatrz surface.

hope this was helpful