<linearGradient
id="linearGradient3706">
<stop
style="stop-color:#ff1c1c;stop-opacity:1;"
offset="0"
id="stop3708" />
<stop
id="stop3728"
offset="0.16105497"
style="stop-color:#fd00ca;stop-opacity:1;" />
<stop
id="stop3724"
offset="0.35173747"
style="stop-color:#0202ff;stop-opacity:1;" />
<stop
id="stop3720"
offset="0.48789391"
style="stop-color:#02fff9;stop-opacity:1;" />
<stop
id="stop3718"
offset="0.70091939"
style="stop-color:#60ff18;stop-opacity:1;" />
<stop
id="stop3714"
offset="0.83720928"
style="stop-color:#ffef15;stop-opacity:1;" />
<stop
style="stop-color:#ff0000;stop-opacity:1;"
offset="1"
id="stop3710" />
</linearGradient>
у меня работает (сделано с инскапе)