Using App variables for easier image indicator

Hi,
In my rich text formulae I'm using below a lot to display status 
"<img src=\"https://images.quickbase.com/si/16/226-rect_gray.png\">"

I tried saving the same as variable called gGrey as "https://images.quickbase.com/si/16/226-rect_gray.png\" and formule as "<img src=\[gGrey]>"  bu this gives blank image. 

Please guide.

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Gunsham Lakhiani
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