Possible Clues:

• In the label the lubricant is back for work for the cutter
• In the label oil is cut back in
• Stone hollowed out by giant oil spill
• Having cut in in the label, oil it up
• In the label the oil comes up for jewellery
• Just a little carving in the label to get the oil back
• In the label, oil is up for carving with a jemmy, perhaps
• The sort of art representing oil giant?
• Fashionable label Ultimo regularly appears — it's a gem
• Engraved or incised design