Technically no, as I am pretty sure those guides are created with CMY dyes, and are not true colors. Its probably a piece of RA4 photographic paper. But I am sure that it works well enough. The Q60 and the IT8 ones are also made in this way, for the specific purpose of profiling the dyes. But they probably still work well enough as well.
The color checker, Macbeth etc are specifically designed for the job at hand.
@ggc 243 in what color representation (HSV, RGB, etc) and which color space (AdobeRGB, sRGB, etc)?
A brief search yielded various conflicting values reported in various forums but nothing that looked authoritative, so also beware of incorrect reference values.
243 r, 240 g, 229 b, in adobe rgb color space.
Anyway i’m trying another way.
I have white balanced the image and i’m filling a gimp color chart i’m creating with sampled values.
Edit: then i’ll try to make them as the Fuji X-T20 one.
I’ve filled all the cells.
But… should i use, in raw therapee to pick colors, no profile or camera standard? Makes a big difference.
camera standard:
no profile:
Meanwhile, i attach the gimp .xcf file with the rulers and the fuji sampled points screenshot always wb adjusted.
@ggc if you have trouble tweaking the colors with the H=f(H) curve in Lab* Tool, you can try to do it in the LHS Equalizer (in the color tab). It has a H=f(H) curve which has more lattitude.
Thank you. Now i’m trying with the g’mic way.
The 2 color charts… unfortunatly the Fuji reaches 255 in a pair of boxes for 1 channel.
.Now i need to update g’mic.
I have generated the lut, and tried. Unfortunatly the result is really 8 bit like, posterized… 
If what you want is make you phone camera’s pictures match roughly those of your XT-20, what i’d do is take a picture of the chart with both cameras.
In RT, open the XT-20 image and in color management, check that the DCP profile is loaded (automatic matching). Now for each patch, make L*, a* and b* measurements. For the grey patches, don’t measure all patches to avoid weird curve shape.
Now load the phone camera image, and create a luminosity tone curve to match roughly the grey patches L* values, avoiding any weird shape.
Then use the H=f(H), L=f(H) and C=f(H) curves in LHS Equalizer to match roughly a* and b* values while keeping the eye on the L* values. You may need to go back and forth between curves as tweaking one may alter the other.
It’s a long process but it should work reasonably well. I’ve used this technique to produce some “Fuji simulation presets” and the results were pretty good.
Thank you again.
For today i give up, and i think even for tomorrow.
Even if it’s far from being ideal, what happens if i take a picture of the macbeth on the monitor with both the fuji and the phone, and use that? (maybe you have already tried…)
Thank you again.
For now i’ve been able to take again the pictures, and i hope they will be ok this time 
@stefan.chirila no in fact I only created a few presets similar to the ones found in Fujifilm X cameras (acros, classic chrome, velvia). So, I don’t have any 400H presets in fortunately.
Have you tried the HaldCLUT that you can get from this collection?
@sguyader
the Halds are great, I have them, but I wanted to know the actual setting in RawTherapee that make it happen Thanks though. Do you have the ones you made uploaded anywhere as pp3?
Yes I have pp3’s, but beware that I think they are full profiles, not partial: FilmSim/ at master · sguyader/FilmSim · GitHub
You can also ping @arangast who made an awesome and more complete set of presets. He provides HaldCLUTS, but maybe can he provide pp3’s if he has them.
@sguyader this is awesome! thank you SO much!
also @arangast would there be any pp3s available perhaps ? would be much appreciated!
@sguyader I downloaded them to my computer but haven’t gotten around to applying them yet. See I’m a weirdo …I love film looks and presets but I can’t bring myself to use them. I like to study them and see what in them makes certain things I like happen …then implement that in my own presets.
In all honesty there are really only two film looks I really care to know about how to emulate; Steve McCurry’s KODACHROME work (think The Afghan Girl …and basically everything he did in the 70s and 80s); and on the other side of the look spectrum, the work of Jose Villa with his overexposed Fujifilm 400H on medium format for weddings.
Steve McCurry:
Jose Villa:
