You may ask from American Society of Horticulture Science

I am aware of colour charts specific for tomatoes , banana and papaya but to say if a universal colour chart exist I am somewhat doubtful given the multitude of colors which may exist. That be said , a chart to describe horticultural colours would be a useful find.

I doubt that universal color charts does exists for all this type part of plants. I more familiar with fruit crops.

Just for references:

1. The colorimeter which can be used for measure color according of RGB

https://www.amazon.com/dp/B00M5UCGSW/?coliid=I1G0XW6O258YZK&colid=2X0E35PCCB1LH&psc=0&ref_=lv_ov_lig_dp_it

2. Universal color charts - there are many. Basically for fruits and leaves I like this:http://www.gomved.com/como-hacer-color-rojo/tutorial-como-hacer-una-infobox-para-tu-wikia-taringa.html

3. Professional charts from CTIFL: http://www.ctifl.fr/Pages/Kiosque/ListeOuvrage.aspx?idType=3

4. professional equipments: http://www.postharvest.biz/en/company/agrosta-sarl/_id:52014,seccion:product_catalog,producto:10216/

Best regards,

Zviad

Dear Mukesh, Marcus and Zviad, thank you very much for your valuable suggestions. I am searching for a free accessible color chart. Thanks

You can go for RHS (Royal Horticulture Society) Colour chart..It is standard..In vegetable releated research this is supposed to be standard.