Edit in JSFiddle

Raphael.fn.pie = function (cx, cy, r, a1, a2) {
    var d, flag = (a2 - a1) > 180;
    
    a1 = (a1 % 360) * Math.PI / 180;
    a2 = (a2 % 360) * Math.PI / 180;
    
    d = ["M", cx, cy, "l", r * Math.cos(a1), r * Math.sin(a1), "A", r, r, "0", +flag, "1", cx + r * Math.cos(a2), cy + r * Math.sin(a2), "z"];
    
    return this.path(d.join(' '));
};


var i, start, end, color,
    nPie  = 24, // Change this value to update the number of pies
    slice = 360/nPie,
    paper = Raphael("paper", 300, 300),
    pies  = paper.set();

for(i = 0; i < nPie; i++) {
    start = (i*slice) - (slice/2);
    end   = start + (360/nPie);
    color = (i*slice) / 360;
    
    pies.push(
        paper.pie(150, 150, 140, start, end)
        .attr({fill:"hsl(" + color + ", 1, 0.5)"})
    );
}

pies.attr({
    stroke: "#FFF",
    "stroke-width": 3 // Change this value to adjust the thickness of the borders.
});

<div id="paper"></div>

body{
    background: black;
    margin: 0;
    padding: 50px
}

#paper{
    width: 300px;
    margin: 0 auto;
}