Use CSS conic-gradient.
Here it's applied to a label with border radius set to 50% all around.
Copy and paste the following into a coordinate view.
Conic gradient label component.
[
{
"type": "ia.display.label",
"version": 0,
"props": {
"style": {
"borderStyle": "solid",
"borderWidth": 1,
"borderColor": "#493F3F",
"borderTopLeftRadius": "50%",
"borderTopRightRadius": "50%",
"borderBottomLeftRadius": "50%",
"borderBottomRightRadius": "50%",
"height": 180,
"background": "conic-gradient(from 230deg at 50% 50%, black, gray, white, black)"
}
},
"meta": {
"name": "ConicGradient"
},
"position": {
"x": 616,
"y": 87,
"height": 180,
"width": 180
},
"custom": {}
}
]