"sweet mother of pearl" meaning in English

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "Of unknown"
      },
      "expansion": "Of unknown",
      "name": "unk"
    }
  ],
  "etymology_text": "Of unknown origins. Attested from the late 19th century.\nPresumably a euphemism for sweet mother of God or sweet mother of Jesus, using mother-of-pearl.",
  "head_templates": [
    {
      "args": {},
      "expansion": "sweet mother of pearl",
      "name": "en-interj"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "intj",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "American English",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "Good gracious; good heavens."
      ],
      "id": "en-sweet_mother_of_pearl-en-intj-0SS2wJ2A",
      "links": [
        [
          "Good gracious",
          "good gracious"
        ],
        [
          "good heavens",
          "good heavens"
        ]
      ],
      "raw_glosses": [
        "(chiefly US, dated) Good gracious; good heavens."
      ],
      "synonyms": [
        {
          "word": "wow"
        }
      ],
      "tags": [
        "US",
        "dated"
      ]
    }
  ],
  "word": "sweet mother of pearl"
}

{
  "etymology_templates": [
    {
      "args": {
        "1": "en",
        "2": "Of unknown"
      },
      "expansion": "Of unknown",
      "name": "unk"
    }
  ],
  "etymology_text": "Of unknown origins. Attested from the late 19th century.\nPresumably a euphemism for sweet mother of God or sweet mother of Jesus, using mother-of-pearl.",
  "head_templates": [
    {
      "args": {},
      "expansion": "sweet mother of pearl",
      "name": "en-interj"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "intj",
  "senses": [
    {
      "categories": [
        "American English",
        "English dated terms",
        "English entries with incorrect language header",
        "English eponyms",
        "English interjections",
        "English lemmas",
        "English multiword terms",
        "English terms with unknown etymologies",
        "Pages with 1 entry",
        "Pages with entries"
      ],
      "glosses": [
        "Good gracious; good heavens."
      ],
      "links": [
        [
          "Good gracious",
          "good gracious"
        ],
        [
          "good heavens",
          "good heavens"
        ]
      ],
      "raw_glosses": [
        "(chiefly US, dated) Good gracious; good heavens."
      ],
      "tags": [
        "US",
        "dated"
      ]
    }
  ],
  "synonyms": [
    {
      "word": "wow"
    }
  ],
  "word": "sweet mother of pearl"
}