JSFiddle - React, Tailwind, and code Playground
HTML
<select name="Pcolor" id="image" style="height:30px;">
<option value="">Избран цвят: Blue/Lt Blue </option>
<option value="45751303" color-number="0">Black</option>
<option value="45751343" color-number="1">Black/Pink</option>
<option value="45751359" color-number="2">Blue/Lt Blue</option>
<option value="45751324" color-number="3">Dk Purple/Purpl</option>
<option value="45751390" color-number="4">Ink/Cerise</option>
</select>
JavaScript
$('#image').on('change',function() {
alert($(this).find('option:selected').attr('color-number'));
})