Question: when did diamonds become popular for engagement rings
[{'answer': 'ancient Rome', 'provenance': [{'wikipedia_id': '39376', 'title': 'Engagement ring', 'start_paragraph_id': 5, 'start_character': 232, 'end_paragraph_id': 5, 'end_character': 244, 'bleu_score': 1.0, 'section': 'Section::::History.:Ancient times.\n'}]}, {'provenance': [{'wikipedia_id': '39376', 'title': 'Engagement ring', 'start_paragraph_id': 5, 'start_character': 0, 'end_paragraph_id': 5, 'end_character': 244, 'bleu_score': 0.9493253852526031, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 10798664884547913398}, 'section': 'Section::::History.:Ancient times.\n'}]}]