Engineered Stone: Shade

Engineered stone is technically known for a homogeneous shade, that is not entirely true. Engineered stone producers publicize that they guarantee same shade, however in big quantities I figure it's very unlikely, due to several factors that effect shade.
What factors may effect the shade of my engineered stone?

• Slab Production factors: during the daily production several batches of raw materials are mixed together, and when dealing with white or beige type colours, little changes may occur that can affect the colouring, namely:
• error in pigment quantity: I know this sounds awkward, but in reality to make a certain colour we normally mix several pigments together, and some are very concentrated and the quantity can be grams ... so being of by a few grams of concentrated blue, may turn your light grey into a light beige;
• exchange on the discharge sequence into the mixer: for those of you familiarized with these production facilities, mixing is one of the most important parts of the process, you may think that every producer has the pigment sequence made by machines .... what if I told you that some producers do it manually .... human error may occur
• raw material quality: in truth when you grind hundreds of tons of quartz, you'll surely have a few tons with a slightly different shade, when producing this factor may cause a slight shade difference between batch productions
• Cleanliness: image a big mixer which just ended a production of a black quartz .... the next step is cleaning, but it's done manually, so the next batch will certainly have some impurities from the batch before. 

• Polishing: people might not give it the importance it deserves, but in my opinion it's where most of the shade problems occur. It can be due to the following: 

• Change in the abrasive sequence between 2 productions: in truth great part of the shade variations arise from the different gloss points the material may have, this can cause uneven slabs, making the tiles cut from the same slab different in shade.
• Production variables: producing with different variables, namely water quantity or velocity of the production line
• Chemical enhancement: some production lines have a chemical applicator, the objective is to enhance the products physical properties and consequently may also affect  the gloss

It's more likely to have a shade problem with you supply when dealing with tiles, especially if the project is big and has to be produced with several batches. When dealing with countertops, it can also occur, depends on the attention the fabricator has regarding these issues, he can easily avoid them by using the same batch material for the job.

Stone tools

Stone tools for quartz or in general for agglomerate stones have some special features. Using stone tools for cutting granite is similar to cutting quartz although these should have certain features which will extend the durability of the tool. Polishing is also known to be very difficult on the dark quartz materials, you can find  good solutions to this in the market, which I plan to explain in detail.
In general, we can say that the same tooling used on natural marble may be used on agglomerate marble. And for quartz agglomerate the tools are similar to the ones used on granite.
Marble based engineered stone:
Cutting: Basically any natural stone marble disc will work with agglomerate marble, and you'll notice a fine cut, as agglomerate marble is easier to work with in the shop;
Polishing edges: use the same abrasives you use on natural marble, however it may be a little more sensitive, so make sure you have good polishing abrasives, especially the yellow ones which make a great difference; In case you polish edges manually, you'll have better results with abrasives that use water, although I have seen good results with dry ones. Marble is really simple to polish, you can manually correct any defect, on the darker colours sometimes you may apply water effect chemical products to give it a nice looking final finishing.
Polishing the surface: Similar to natural marble, although you might have some difficulty in attaining the same shine, normally the shine for marble based materials is between 70-85. In some colours it may be difficult to get a perfect polish, the bigger the grain (refering to the texture of the material) used the easier it is to polish, of course darker colours are always difficult.
Quartz based engineered stone:

Cutting: quartz is much harder than granite, so expect it to consume a bit more diamond. A good diamond disc for cutting quartz should have a special diamond feature on the side of the disc as my picture below (marked in red).

Normal granite discs will consume the metal sides while manually cutting quartz, I've seen discs literally break before the diamond on the cutting edge is totally consumed. When you use it manually, you can never guarantee a 90º angle so the sides of the disc will make contact with the stone. Also use water while cutting quartz to refresh the disc, you'll expand your discs lifetime.
Polishing edges: Try the diamond flexible pads on you quartz edges, it has given me the best results, they are expensive but they'll give you a very good finish. Many salesmen will show you dozens of solutions, however they are trying to sell the products they carry, I have tested normal abrasives, cyclone type, moving heads on edge polishers, and the ones that work best as I mentioned are the flexible diamond pads. I won't talk about brands, because I have no intention on selling, but I think you should test what you may have available in your local market. You can also use the water efffect chemical products on these edges, it really improves the final finish.
Polishing the surface: Forget it, don't even try, you'll end up destroying your quartz piece.