Generally i have seen purple and white colour of brinjal but recently i saw a brinjal in yellow colour. I asked someone perhaps he was the owner of vegetables field about yellow colour of brinjal he replied “as you are looking that approximately all brinjals are in purple colour but one of them in yellow colour and reason behind it is profit and i will utilise it in next farming”. Means when it will dry naturally he will use its seeds in next farming. Yeah! it is really awesome way to arrange seeds in home instead of purchasing every season.
Please have a look at photos:
Here in last photo you can see some cut marks and reason behind it is that natural air can enter as required. Too much techniques available region by region.