Here is a color palette based on the “Sorrow” theme with red, green, blue, black, and white, including two additional colors to complete the request for seven colors.

json
{
  "palette_name": "Sorrow Theme Palette",
  "colors": [
    {
      "name": "Deep Red",
      "hex_code": "
          
          #8B0000
       "
    },
    {
      "name": "Dark Green",
      "hex_code": "
          
          #006400
       "
    },
    {
      "name": "Dark Blue",
      "hex_code": "
          
          #00008B
       "
    },
    {
      "name": "Black",
      "hex_code": "
          
          #000000
       "
    },
    {
      "name": "White",
      "hex_code": "
          
          #FFFFFF
       "
    },
    {
      "name": "Gray",
      "hex_code": "
          
          #808080
       "
    },
    {
      "name": "Muted Purple",
      "hex_code": "
          
          #6A5ACD
       "
    }
  ]
}

This palette uses darker tones and muted colors to evoke a sense of sorrow and melancholy, while still incorporating the requested colors.

Would you like to explore more about how to use this palette? Or do you need assistance with something else?